diff --git a/en_US.ISO8859-1/books/handbook/disks/chapter.sgml b/en_US.ISO8859-1/books/handbook/disks/chapter.sgml index 92ff4623b1..63c6f02f77 100644 --- a/en_US.ISO8859-1/books/handbook/disks/chapter.sgml +++ b/en_US.ISO8859-1/books/handbook/disks/chapter.sgml @@ -1,4142 +1,4148 @@ Storage Synopsis This chapter covers the use of disks in FreeBSD. This includes memory-backed disks, network-attached disks, standard SCSI/IDE storage devices, and devices using the USB interface. After reading this chapter, you will know: The terminology FreeBSD uses to describe the organization of data on a physical disk (partitions and slices). How to add additional hard disks to your system. How to configure &os; to use USB storage devices. How to set up virtual file systems, such as memory disks. How to use quotas to limit disk space usage. How to encrypt disks to secure them against attackers. How to create and burn CDs and DVDs on FreeBSD. The various storage media options for backups. How to use backup programs available under FreeBSD. How to backup to floppy disks. What file system snapshots are and how to use them efficiently. Before reading this chapter, you should: Know how to configure and install a new FreeBSD kernel (). Device Names The following is a list of physical storage devices supported in FreeBSD, and the device names associated with them. Physical Disk Naming Conventions Drive type Drive device name IDE hard drives ad IDE CDROM drives acd SCSI hard drives and USB Mass storage devices da SCSI CDROM drives cd Assorted non-standard CDROM drives mcd for Mitsumi CD-ROM and scd for Sony CD-ROM devices Floppy drives fd SCSI tape drives sa IDE tape drives ast Flash drives fla for &diskonchip; Flash device RAID drives aacd for &adaptec; AdvancedRAID, mlxd and mlyd for &mylex;, amrd for AMI &megaraid;, idad for Compaq Smart RAID, twed for &tm.3ware; RAID.
David O'Brien Originally contributed by Adding Disks disks adding Lets say we want to add a new SCSI disk to a machine that currently only has a single drive. First turn off the computer and install the drive in the computer following the instructions of the computer, controller, and drive manufacturer. Due to the wide variations of procedures to do this, the details are beyond the scope of this document. Login as user root. After you have installed the drive, inspect /var/run/dmesg.boot to ensure the new disk was found. Continuing with our example, the newly added drive will be da1 and we want to mount it on /1 (if you are adding an IDE drive, the device name will be ad1). partitions slices fdisk FreeBSD runs on IBM-PC compatible computers, therefore it must take into account the PC BIOS partitions. These are different from the traditional BSD partitions. A PC disk has up to four BIOS partition entries. If the disk is going to be truly dedicated to FreeBSD, you can use the dedicated mode. Otherwise, FreeBSD will have to live within one of the PC BIOS partitions. FreeBSD calls the PC BIOS partitions slices so as not to confuse them with traditional BSD partitions. You may also use slices on a disk that is dedicated to FreeBSD, but used in a computer that also has another operating system installed. This is a good way to avoid confusing the fdisk utility of other, non-FreeBSD operating systems. In the slice case the drive will be added as /dev/da1s1e. This is read as: SCSI disk, unit number 1 (second SCSI disk), slice 1 (PC BIOS partition 1), and e BSD partition. In the dedicated case, the drive will be added simply as /dev/da1e. Due to the use of 32-bit integers to store the number of sectors, &man.bsdlabel.8; is limited to 2^32-1 sectors per disk or 2TB in most cases. The &man.fdisk.8; format allows a starting sector of no more than 2^32-1 and a length of no more than 2^32-1, limiting partitions to 2TB and disks to 4TB in most cases. The &man.sunlabel.8; format is limited to 2^32-1 sectors per partition and 8 partitions for a total of 16TB. For larger disks, &man.gpt.8; partitions may be used. Using &man.sysinstall.8; sysinstall adding disks su Navigating <application>Sysinstall</application> You may use sysinstall to partition and label a new disk using its easy to use menus. Either login as user root or use the su command. Run sysinstall and enter the Configure menu. Within the FreeBSD Configuration Menu, scroll down and select the Fdisk option. <application>fdisk</application> Partition Editor Once inside fdisk, typing A will use the entire disk for FreeBSD. When asked if you want to remain cooperative with any future possible operating systems, answer YES. Write the changes to the disk using W. Now exit the FDISK editor by typing q. Next you will be asked about the Master Boot Record. Since you are adding a disk to an already running system, choose None. Disk Label Editor BSD partitions Next, you need to exit sysinstall and start it again. Follow the directions above, although this time choose the Label option. This will enter the Disk Label Editor. This is where you will create the traditional BSD partitions. A disk can have up to eight partitions, labeled a-h. A few of the partition labels have special uses. The a partition is used for the root partition (/). Thus only your system disk (e.g, the disk you boot from) should have an a partition. The b partition is used for swap partitions, and you may have many disks with swap partitions. The c partition addresses the entire disk in dedicated mode, or the entire FreeBSD slice in slice mode. The other partitions are for general use. sysinstall's Label editor favors the e partition for non-root, non-swap partitions. Within the Label editor, create a single file system by typing C. When prompted if this will be a FS (file system) or swap, choose FS and type in a mount point (e.g, /mnt). When adding a disk in post-install mode, sysinstall will not create entries in /etc/fstab for you, so the mount point you specify is not important. You are now ready to write the new label to the disk and create a file system on it. Do this by typing W. Ignore any errors from sysinstall that it could not mount the new partition. Exit the Label Editor and sysinstall completely. Finish The last step is to edit /etc/fstab to add an entry for your new disk. Using Command Line Utilities Using Slices This setup will allow your disk to work correctly with other operating systems that might be installed on your computer and will not confuse other operating systems' fdisk utilities. It is recommended to use this method for new disk installs. Only use dedicated mode if you have a good reason to do so! &prompt.root; dd if=/dev/zero of=/dev/da1 bs=1k count=1 &prompt.root; fdisk -BI da1 #Initialize your new disk &prompt.root; bsdlabel -B -w -r da1s1 auto #Label it. &prompt.root; bsdlabel -e da1s1 # Edit the bsdlabel just created and add any partitions. &prompt.root; mkdir -p /1 &prompt.root; newfs /dev/da1s1e # Repeat this for every partition you created. &prompt.root; mount /dev/da1s1e /1 # Mount the partition(s) &prompt.root; vi /etc/fstab # Add the appropriate entry/entries to your /etc/fstab. If you have an IDE disk, substitute ad for da. Dedicated OS/2 If you will not be sharing the new drive with another operating system, you may use the dedicated mode. Remember this mode can confuse Microsoft operating systems; however, no damage will be done by them. IBM's &os2; however, will appropriate any partition it finds which it does not understand. &prompt.root; dd if=/dev/zero of=/dev/da1 bs=1k count=1 &prompt.root; bsdlabel -Brw da1 auto &prompt.root; bsdlabel -e da1 # create the `e' partition &prompt.root; newfs -d0 /dev/da1e &prompt.root; mkdir -p /1 &prompt.root; vi /etc/fstab # add an entry for /dev/da1e &prompt.root; mount /1 An alternate method is: &prompt.root; dd if=/dev/zero of=/dev/da1 count=2 &prompt.root; bsdlabel /dev/da1 | bsdlabel -BrR da1 /dev/stdin &prompt.root; newfs /dev/da1e &prompt.root; mkdir -p /1 &prompt.root; vi /etc/fstab # add an entry for /dev/da1e &prompt.root; mount /1 RAID Software RAID Christopher Shumway Original work by Jim Brown Revised by RAIDsoftware RAIDCCD Concatenated Disk Driver (CCD) Configuration When choosing a mass storage solution the most important factors to consider are speed, reliability, and cost. It is rare to have all three in balance; normally a fast, reliable mass storage device is expensive, and to cut back on cost either speed or reliability must be sacrificed. In designing the system described below, cost was chosen as the most important factor, followed by speed, then reliability. Data transfer speed for this system is ultimately constrained by the network. And while reliability is very important, the CCD drive described below serves online data that is already fully backed up on CD-R's and can easily be replaced. Defining your own requirements is the first step in choosing a mass storage solution. If your requirements prefer speed or reliability over cost, your solution will differ from the system described in this section. Installing the Hardware In addition to the IDE system disk, three Western Digital 30GB, 5400 RPM IDE disks form the core of the CCD disk described below providing approximately 90GB of online storage. Ideally, each IDE disk would have its own IDE controller and cable, but to minimize cost, additional IDE controllers were not used. Instead the disks were configured with jumpers so that each IDE controller has one master, and one slave. Upon reboot, the system BIOS was configured to automatically detect the disks attached. More importantly, FreeBSD detected them on reboot: ad0: 19574MB <WDC WD205BA> [39770/16/63] at ata0-master UDMA33 ad1: 29333MB <WDC WD307AA> [59598/16/63] at ata0-slave UDMA33 ad2: 29333MB <WDC WD307AA> [59598/16/63] at ata1-master UDMA33 ad3: 29333MB <WDC WD307AA> [59598/16/63] at ata1-slave UDMA33 If FreeBSD does not detect all the disks, ensure that you have jumpered them correctly. Most IDE drives also have a Cable Select jumper. This is not the jumper for the master/slave relationship. Consult the drive documentation for help in identifying the correct jumper. Next, consider how to attach them as part of the file system. You should research both &man.vinum.8; () and &man.ccd.4;. In this particular configuration, &man.ccd.4; was chosen. Setting Up the CCD The &man.ccd.4; driver allows you to take several identical disks and concatenate them into one logical file system. In order to use &man.ccd.4;, you need a kernel with &man.ccd.4; support built in. Add this line to your kernel configuration file, rebuild, and reinstall the kernel: device ccd The &man.ccd.4; support can also be loaded as a kernel loadable module. To set up &man.ccd.4;, you must first use &man.bsdlabel.8; to label the disks: bsdlabel -r -w ad1 auto bsdlabel -r -w ad2 auto bsdlabel -r -w ad3 auto This creates a bsdlabel for ad1c, ad2c and ad3c that spans the entire disk. The next step is to change the disk label type. You can use &man.bsdlabel.8; to edit the disks: bsdlabel -e ad1 bsdlabel -e ad2 bsdlabel -e ad3 This opens up the current disk label on each disk with the editor specified by the EDITOR environment variable, typically &man.vi.1;. An unmodified disk label will look something like this: 8 partitions: # size offset fstype [fsize bsize bps/cpg] c: 60074784 0 unused 0 0 0 # (Cyl. 0 - 59597) Add a new e partition for &man.ccd.4; to use. This can usually be copied from the c partition, but the must be 4.2BSD. The disk label should now look something like this: 8 partitions: # size offset fstype [fsize bsize bps/cpg] c: 60074784 0 unused 0 0 0 # (Cyl. 0 - 59597) e: 60074784 0 4.2BSD 0 0 0 # (Cyl. 0 - 59597) Building the File System Now that you have all the disks labeled, you must build the &man.ccd.4;. To do that, use &man.ccdconfig.8;, with options similar to the following: ccdconfig ccd0 32 0 /dev/ad1e /dev/ad2e /dev/ad3e The use and meaning of each option is shown below: The first argument is the device to configure, in this case, /dev/ccd0c. The /dev/ portion is optional. The interleave for the file system. The interleave defines the size of a stripe in disk blocks, each normally 512 bytes. So, an interleave of 32 would be 16,384 bytes. Flags for &man.ccdconfig.8;. If you want to enable drive mirroring, you can specify a flag here. This configuration does not provide mirroring for &man.ccd.4;, so it is set at 0 (zero). The final arguments to &man.ccdconfig.8; are the devices to place into the array. Use the complete pathname for each device. After running &man.ccdconfig.8; the &man.ccd.4; is configured. A file system can be installed. Refer to &man.newfs.8; for options, or simply run: newfs /dev/ccd0c Making it All Automatic Generally, you will want to mount the &man.ccd.4; upon each reboot. To do this, you must configure it first. Write out your current configuration to /etc/ccd.conf using the following command: ccdconfig -g > /etc/ccd.conf During reboot, the script /etc/rc runs ccdconfig -C if /etc/ccd.conf exists. This automatically configures the &man.ccd.4; so it can be mounted. If you are booting into single user mode, before you can &man.mount.8; the &man.ccd.4;, you need to issue the following command to configure the array: ccdconfig -C To automatically mount the &man.ccd.4;, place an entry for the &man.ccd.4; in /etc/fstab so it will be mounted at boot time: /dev/ccd0c /media ufs rw 2 2 The Vinum Volume Manager RAIDsoftware RAID Vinum The Vinum Volume Manager is a block device driver which implements virtual disk drives. It isolates disk hardware from the block device interface and maps data in ways which result in an increase in flexibility, performance and reliability compared to the traditional slice view of disk storage. &man.vinum.8; implements the RAID-0, RAID-1 and RAID-5 models, both individually and in combination. See for more information about &man.vinum.8;. Hardware RAID RAID hardware FreeBSD also supports a variety of hardware RAID controllers. These devices control a RAID subsystem without the need for FreeBSD specific software to manage the array. Using an on-card BIOS, the card controls most of the disk operations itself. The following is a brief setup description using a Promise IDE RAID controller. When this card is installed and the system is started up, it displays a prompt requesting information. Follow the instructions to enter the card's setup screen. From here, you have the ability to combine all the attached drives. After doing so, the disk(s) will look like a single drive to FreeBSD. Other RAID levels can be set up accordingly. Rebuilding ATA RAID1 Arrays FreeBSD allows you to hot-replace a failed disk in an array. This requires that you catch it before you reboot. You will probably see something like the following in /var/log/messages or in the &man.dmesg.8; output: ad6 on monster1 suffered a hard error. ad6: READ command timeout tag=0 serv=0 - resetting ad6: trying fallback to PIO mode ata3: resetting devices .. done ad6: hard error reading fsbn 1116119 of 0-7 (ad6 bn 1116119; cn 1107 tn 4 sn 11)\\ status=59 error=40 ar0: WARNING - mirror lost Using &man.atacontrol.8;, check for further information: &prompt.root; atacontrol list ATA channel 0: Master: no device present Slave: acd0 <HL-DT-ST CD-ROM GCR-8520B/1.00> ATA/ATAPI rev 0 ATA channel 1: Master: no device present Slave: no device present ATA channel 2: Master: ad4 <MAXTOR 6L080J4/A93.0500> ATA/ATAPI rev 5 Slave: no device present ATA channel 3: Master: ad6 <MAXTOR 6L080J4/A93.0500> ATA/ATAPI rev 5 Slave: no device present &prompt.root; atacontrol status ar0 ar0: ATA RAID1 subdisks: ad4 ad6 status: DEGRADED You will first need to detach the ata channel with the failed disk so you can safely remove it: &prompt.root; atacontrol detach ata3 Replace the disk. Reattach the ata channel: &prompt.root; atacontrol attach ata3 Master: ad6 <MAXTOR 6L080J4/A93.0500> ATA/ATAPI rev 5 Slave: no device present Add the new disk to the array as a spare: &prompt.root; atacontrol addspare ar0 ad6 Rebuild the array: &prompt.root; atacontrol rebuild ar0 It is possible to check on the progress by issuing the following command: &prompt.root; dmesg | tail -10 [output removed] ad6: removed from configuration ad6: deleted from ar0 disk1 ad6: inserted into ar0 disk1 as spare &prompt.root; atacontrol status ar0 ar0: ATA RAID1 subdisks: ad4 ad6 status: REBUILDING 0% completed Wait until this operation completes. Marc Fonvieille Contributed by USB Storage Devices USB disks A lot of external storage solutions, nowadays, use the Universal Serial Bus (USB): hard drives, USB thumbdrives, CD-R burners, etc. &os; provides support for these devices. Configuration The USB mass storage devices driver, &man.umass.4;, provides the support for USB storage devices. If you use the GENERIC kernel, you do not have to change anything in your configuration. If you use a custom kernel, be sure that the following lines are present in your kernel configuration file: device scbus device da device pass device uhci device ohci device usb device umass The &man.umass.4; driver uses the SCSI subsystem to access to the USB storage devices, your USB device will be seen as a SCSI device by the system. Depending on the USB chipset on your motherboard, you only need either device uhci or device ohci, however having both in the kernel configuration file is harmless. Do not forget to compile and install the new kernel if you added any lines. If your USB device is a CD-R or DVD burner, the SCSI CD-ROM driver, &man.cd.4;, must be added to the kernel via the line: device cd Since the burner is seen as a SCSI drive, the driver &man.atapicam.4; should not be used in the kernel configuration. Support for USB 2.0 controllers is provided on &os;; however, you must add: device ehci to your configuration file for USB 2.0 support. Note &man.uhci.4; and &man.ohci.4; drivers are still needed if you want USB 1.X support. Testing the Configuration The configuration is ready to be tested: plug in your USB device, and in the system message buffer (&man.dmesg.8;), the drive should appear as something like: umass0: USB Solid state disk, rev 1.10/1.00, addr 2 GEOM: create disk da0 dp=0xc2d74850 da0 at umass-sim0 bus 0 target 0 lun 0 da0: <Generic Traveling Disk 1.11> Removable Direct Access SCSI-2 device da0: 1.000MB/s transfers da0: 126MB (258048 512 byte sectors: 64H 32S/T 126C) Of course, the brand, the device node (da0) and other details can differ according to your configuration. Since the USB device is seen as a SCSI one, the camcontrol command can be used to list the USB storage devices attached to the system: &prompt.root; camcontrol devlist <Generic Traveling Disk 1.11> at scbus0 target 0 lun 0 (da0,pass0) If the drive comes with a file system, you should be able to mount it. The will help you to format and create partitions on the USB drive if needed. To make this device mountable as a normal user, certain steps have to be taken. First, the devices that are created when a USB storage device is connected need to be accessible by the user. A solution is to make all users of these devices a member of the operator group. This is done with &man.pw.8;. Second, when the devices are created, the operator group should be - able to read and write them. This is accomplished by adding a - line for these devices to + able to read and write them. This is accomplished by adding + these lines to /etc/devfs.rules: - add path 'da*' mode 0660 group operator + [localrules=1] +add path 'da*' mode 0660 group operator If there already are SCSI disks in the system, it must be done a bit different. E.g., if the system already contains disks da0 through da2 attached to the system, change - the line as follows: + the second line as follows: add path 'da[3-9]*' mode 0660 group operator This will exclude the already existing disks from belonging to the operator group. + You also have to enable your &man.devfs.rules.5;; ruleset + in your /etc/rc.conf file: + + devfs_system_ruleset="localrules" + Next, the kernel has to be configured to allow regular users to mount file systems. The easiest way is to add the following line to /etc/sysctl.conf: vfs.usermount=1 Note that this only takes effect after the next reboot. Alternatively, one can also use &man.sysctl.8; to set this variable. The final step is to create a directory where the file system is to be mounted. This directory needs to be owned by the user that is to mount the file system. One way to do that is for root to create a subdirectory owned by that user as /mnt/$USER (replace $USER by the login name of the actual user): &prompt.root; mkdir /mnt/$USER &prompt.root; chown $USER:$USER /mnt/$USER Suppose a USB thumbdrive is plugged in, and a device /dev/da0s1 appears. Since these devices usually come preformatted with a FAT file system, one can mount them like this: &prompt.user; mount_msdosfs -m 644 -M 755 /dev/da0s1 /mnt/$USER If you unplug the device (the disk must be unmounted before), you should see, in the system message buffer, something like the following: umass0: at uhub0 port 1 (addr 2) disconnected (da0:umass-sim0:0:0:0): lost device (da0:umass-sim0:0:0:0): removing device entry GEOM: destroy disk da0 dp=0xc2d74850 umass0: detached Further Reading Beside the Adding Disks and Mounting and Unmounting File Systems sections, reading various manual pages may be also useful: &man.umass.4;, &man.camcontrol.8;, and &man.usbdevs.8;. Mike Meyer Contributed by Creating and Using Optical Media (CDs) CDROMs creating Introduction CDs have a number of features that differentiate them from conventional disks. Initially, they were not writable by the user. They are designed so that they can be read continuously without delays to move the head between tracks. They are also much easier to transport between systems than similarly sized media were at the time. CDs do have tracks, but this refers to a section of data to be read continuously and not a physical property of the disk. To produce a CD on FreeBSD, you prepare the data files that are going to make up the tracks on the CD, then write the tracks to the CD. ISO 9660 file systems ISO 9660 The ISO 9660 file system was designed to deal with these differences. It unfortunately codifies file system limits that were common then. Fortunately, it provides an extension mechanism that allows properly written CDs to exceed those limits while still working with systems that do not support those extensions. sysutils/cdrtools The sysutils/cdrtools port includes &man.mkisofs.8;, a program that you can use to produce a data file containing an ISO 9660 file system. It has options that support various extensions, and is described below. CD burner ATAPI Which tool to use to burn the CD depends on whether your CD burner is ATAPI or something else. ATAPI CD burners use the burncd program that is part of the base system. SCSI and USB CD burners should use cdrecord from the sysutils/cdrtools port. It is also possible to use cdrecord and other tools for SCSI drives on ATAPI hardware with the ATAPI/CAM module. If you want CD burning software with a graphical user interface, you may wish to take a look at either X-CD-Roast or K3b. These tools are available as packages or from the sysutils/xcdroast and sysutils/k3b ports. X-CD-Roast and K3b require the ATAPI/CAM module with ATAPI hardware. mkisofs The &man.mkisofs.8; program, which is part of the sysutils/cdrtools port, produces an ISO 9660 file system that is an image of a directory tree in the &unix; file system name space. The simplest usage is: &prompt.root; mkisofs -o imagefile.iso /path/to/tree file systems ISO 9660 This command will create an imagefile.iso containing an ISO 9660 file system that is a copy of the tree at /path/to/tree. In the process, it will map the file names to names that fit the limitations of the standard ISO 9660 file system, and will exclude files that have names uncharacteristic of ISO file systems. file systems HFS file systems Joliet A number of options are available to overcome those restrictions. In particular, enables the Rock Ridge extensions common to &unix; systems, enables Joliet extensions used by Microsoft systems, and can be used to create HFS file systems used by &macos;. For CDs that are going to be used only on FreeBSD systems, can be used to disable all filename restrictions. When used with , it produces a file system image that is identical to the FreeBSD tree you started from, though it may violate the ISO 9660 standard in a number of ways. CDROMs creating bootable The last option of general use is . This is used to specify the location of the boot image for use in producing an El Torito bootable CD. This option takes an argument which is the path to a boot image from the top of the tree being written to the CD. By default, &man.mkisofs.8; creates an ISO image in the so-called floppy disk emulation mode, and thus expects the boot image to be exactly 1200, 1440 or 2880 KB in size. Some boot loaders, like the one used by the FreeBSD distribution disks, do not use emulation mode; in this case, the option should be used. So, if /tmp/myboot holds a bootable FreeBSD system with the boot image in /tmp/myboot/boot/cdboot, you could produce the image of an ISO 9660 file system in /tmp/bootable.iso like so: &prompt.root; mkisofs -R -no-emul-boot -b boot/cdboot -o /tmp/bootable.iso /tmp/myboot Having done that, if you have md configured in your kernel, you can mount the file system with: &prompt.root; mdconfig -a -t vnode -f /tmp/bootable.iso -u 0 &prompt.root; mount -t cd9660 /dev/md0 /mnt At which point you can verify that /mnt and /tmp/myboot are identical. There are many other options you can use with &man.mkisofs.8; to fine-tune its behavior. In particular: modifications to an ISO 9660 layout and the creation of Joliet and HFS discs. See the &man.mkisofs.8; manual page for details. burncd CDROMs burning If you have an ATAPI CD burner, you can use the burncd command to burn an ISO image onto a CD. burncd is part of the base system, installed as /usr/sbin/burncd. Usage is very simple, as it has few options: &prompt.root; burncd -f cddevice data imagefile.iso fixate Will burn a copy of imagefile.iso on cddevice. The default device is /dev/acd0. See &man.burncd.8; for options to set the write speed, eject the CD after burning, and write audio data. cdrecord If you do not have an ATAPI CD burner, you will have to use cdrecord to burn your CDs. cdrecord is not part of the base system; you must install it from either the port at sysutils/cdrtools or the appropriate package. Changes to the base system can cause binary versions of this program to fail, possibly resulting in a coaster. You should therefore either upgrade the port when you upgrade your system, or if you are tracking -STABLE, upgrade the port when a new version becomes available. While cdrecord has many options, basic usage is even simpler than burncd. Burning an ISO 9660 image is done with: &prompt.root; cdrecord dev=device imagefile.iso The tricky part of using cdrecord is finding the to use. To find the proper setting, use the flag of cdrecord, which might produce results like this: CDROMs burning &prompt.root; cdrecord -scanbus Cdrecord-Clone 2.01 (i386-unknown-freebsd7.0) Copyright (C) 1995-2004 Jörg Schilling Using libscg version 'schily-0.1' scsibus0: 0,0,0 0) 'SEAGATE ' 'ST39236LW ' '0004' Disk 0,1,0 1) 'SEAGATE ' 'ST39173W ' '5958' Disk 0,2,0 2) * 0,3,0 3) 'iomega ' 'jaz 1GB ' 'J.86' Removable Disk 0,4,0 4) 'NEC ' 'CD-ROM DRIVE:466' '1.26' Removable CD-ROM 0,5,0 5) * 0,6,0 6) * 0,7,0 7) * scsibus1: 1,0,0 100) * 1,1,0 101) * 1,2,0 102) * 1,3,0 103) * 1,4,0 104) * 1,5,0 105) 'YAMAHA ' 'CRW4260 ' '1.0q' Removable CD-ROM 1,6,0 106) 'ARTEC ' 'AM12S ' '1.06' Scanner 1,7,0 107) * This lists the appropriate value for the devices on the list. Locate your CD burner, and use the three numbers separated by commas as the value for . In this case, the CRW device is 1,5,0, so the appropriate input would be . There are easier ways to specify this value; see &man.cdrecord.1; for details. That is also the place to look for information on writing audio tracks, controlling the speed, and other things. Duplicating Audio CDs You can duplicate an audio CD by extracting the audio data from the CD to a series of files, and then writing these files to a blank CD. The process is slightly different for ATAPI and SCSI drives. SCSI Drives Use cdda2wav to extract the audio. &prompt.user; cdda2wav -v255 -D2,0 -B -Owav Use cdrecord to write the .wav files. &prompt.user; cdrecord -v dev=2,0 -dao -useinfo *.wav Make sure that 2,0 is set appropriately, as described in . ATAPI Drives The ATAPI CD driver makes each track available as /dev/acddtnn, where d is the drive number, and nn is the track number written with two decimal digits, prefixed with zero as needed. So the first track on the first disk is /dev/acd0t01, the second is /dev/acd0t02, the third is /dev/acd0t03, and so on. Make sure the appropriate files exist in /dev. If the entries are missing, force the system to retaste the media: &prompt.root; dd if=/dev/acd0 of=/dev/null count=1 Extract each track using &man.dd.1;. You must also use a specific block size when extracting the files. &prompt.root; dd if=/dev/acd0t01 of=track1.cdr bs=2352 &prompt.root; dd if=/dev/acd0t02 of=track2.cdr bs=2352 ... Burn the extracted files to disk using burncd. You must specify that these are audio files, and that burncd should fixate the disk when finished. &prompt.root; burncd -f /dev/acd0 audio track1.cdr track2.cdr ... fixate Duplicating Data CDs You can copy a data CD to a image file that is functionally equivalent to the image file created with &man.mkisofs.8;, and you can use it to duplicate any data CD. The example given here assumes that your CDROM device is acd0. Substitute your correct CDROM device. &prompt.root; dd if=/dev/acd0 of=file.iso bs=2048 Now that you have an image, you can burn it to CD as described above. Using Data CDs Now that you have created a standard data CDROM, you probably want to mount it and read the data on it. By default, &man.mount.8; assumes that a file system is of type ufs. If you try something like: &prompt.root; mount /dev/cd0 /mnt you will get a complaint about Incorrect super block, and no mount. The CDROM is not a UFS file system, so attempts to mount it as such will fail. You just need to tell &man.mount.8; that the file system is of type ISO9660, and everything will work. You do this by specifying the option &man.mount.8;. For example, if you want to mount the CDROM device, /dev/cd0, under /mnt, you would execute: &prompt.root; mount -t cd9660 /dev/cd0 /mnt Note that your device name (/dev/cd0 in this example) could be different, depending on the interface your CDROM uses. Also, the option just executes &man.mount.cd9660.8;. The above example could be shortened to: &prompt.root; mount_cd9660 /dev/cd0 /mnt You can generally use data CDROMs from any vendor in this way. Disks with certain ISO 9660 extensions might behave oddly, however. For example, Joliet disks store all filenames in two-byte Unicode characters. The FreeBSD kernel does not speak Unicode, but the &os; CD9660 driver is able to convert Unicode characters on the fly. If some non-English characters show up as question marks you will need to specify the local charset you use with the option. For more information, consult the &man.mount.cd9660.8; manual page. To be able to do this character conversion with the help of the option, the kernel will require the cd9660_iconv.ko module to be loaded. This can be done either by adding this line to loader.conf: cd9660_iconv_load="YES" and then rebooting the machine, or by directly loading the module with &man.kldload.8;. Occasionally, you might get Device not configured when trying to mount a CDROM. This usually means that the CDROM drive thinks that there is no disk in the tray, or that the drive is not visible on the bus. It can take a couple of seconds for a CDROM drive to realize that it has been fed, so be patient. Sometimes, a SCSI CDROM may be missed because it did not have enough time to answer the bus reset. If you have a SCSI CDROM please add the following option to your kernel configuration and rebuild your kernel. options SCSI_DELAY=15000 This tells your SCSI bus to pause 15 seconds during boot, to give your CDROM drive every possible chance to answer the bus reset. Burning Raw Data CDs You can choose to burn a file directly to CD, without creating an ISO 9660 file system. Some people do this for backup purposes. This runs more quickly than burning a standard CD: &prompt.root; burncd -f /dev/acd1 -s 12 data archive.tar.gz fixate In order to retrieve the data burned to such a CD, you must read data from the raw device node: &prompt.root; tar xzvf /dev/acd1 You cannot mount this disk as you would a normal CDROM. Such a CDROM cannot be read under any operating system except FreeBSD. If you want to be able to mount the CD, or share data with another operating system, you must use &man.mkisofs.8; as described above. Marc Fonvieille Contributed by CD burner ATAPI/CAM driver Using the ATAPI/CAM Driver This driver allows ATAPI devices (CD-ROM, CD-RW, DVD drives etc...) to be accessed through the SCSI subsystem, and so allows the use of applications like sysutils/cdrdao or &man.cdrecord.1;. To use this driver, you will need to add the following line to the /boot/loader.conf file: atapicam_load="YES" then, reboot your machine. If you prefer to statically compile the &man.atapicam.4; support in your kernel, you will have to add this line to your kernel configuration file: device atapicam You also need the following lines in your kernel configuration file: device ata device scbus device cd device pass which should already be present. Then rebuild, install your new kernel, and reboot your machine. During the boot process, your burner should show up, like so: acd0: CD-RW <MATSHITA CD-RW/DVD-ROM UJDA740> at ata1-master PIO4 cd0 at ata1 bus 0 target 0 lun 0 cd0: <MATSHITA CDRW/DVD UJDA740 1.00> Removable CD-ROM SCSI-0 device cd0: 16.000MB/s transfers cd0: Attempt to query device size failed: NOT READY, Medium not present - tray closed The drive could now be accessed via the /dev/cd0 device name, for example to mount a CD-ROM on /mnt, just type the following: &prompt.root; mount -t cd9660 /dev/cd0 /mnt As root, you can run the following command to get the SCSI address of the burner: &prompt.root; camcontrol devlist <MATSHITA CDRW/DVD UJDA740 1.00> at scbus1 target 0 lun 0 (pass0,cd0) So 1,0,0 will be the SCSI address to use with &man.cdrecord.1; and other SCSI application. For more information about ATAPI/CAM and SCSI system, refer to the &man.atapicam.4; and &man.cam.4; manual pages. Marc Fonvieille Contributed by Andy Polyakov With inputs from Creating and Using Optical Media (DVDs) DVD burning Introduction Compared to the CD, the DVD is the next generation of optical media storage technology. The DVD can hold more data than any CD and is nowadays the standard for video publishing. Five physical recordable formats can be defined for what we will call a recordable DVD: DVD-R: This was the first DVD recordable format available. The DVD-R standard is defined by the DVD Forum. This format is write once. DVD-RW: This is the rewritable version of the DVD-R standard. A DVD-RW can be rewritten about 1000 times. DVD-RAM: This is also a rewritable format supported by the DVD Forum. A DVD-RAM can be seen as a removable hard drive. However, this media is not compatible with most DVD-ROM drives and DVD-Video players; only a few DVD writers support the DVD-RAM format. Read the for more information on DVD-RAM use. DVD+RW: This is a rewritable format defined by the DVD+RW Alliance. A DVD+RW can be rewritten about 1000 times. DVD+R: This format is the write once variation of the DVD+RW format. A single layer recordable DVD can hold up to 4,700,000,000 bytes which is actually 4.38 GB or 4485 MB (1 kilobyte is 1024 bytes). A distinction must be made between the physical media and the application. For example, a DVD-Video is a specific file layout that can be written on any recordable DVD physical media: DVD-R, DVD+R, DVD-RW etc. Before choosing the type of media, you must be sure that both the burner and the DVD-Video player (a standalone player or a DVD-ROM drive on a computer) are compatible with the media under consideration. Configuration The program &man.growisofs.1; will be used to perform DVD recording. This command is part of the dvd+rw-tools utilities (sysutils/dvd+rw-tools). The dvd+rw-tools support all DVD media types. These tools use the SCSI subsystem to access to the devices, therefore the ATAPI/CAM support must be added to your kernel. If your burner uses the USB interface this addition is useless, and you should read the for more details on USB devices configuration. You also have to enable DMA access for ATAPI devices, this can be done in adding the following line to the /boot/loader.conf file: hw.ata.atapi_dma="1" Before attempting to use the dvd+rw-tools you should consult the dvd+rw-tools' hardware compatibility notes for any information related to your DVD burner. If you want a graphical user interface, you should have a look to K3b (sysutils/k3b) which provides a user friendly interface to &man.growisofs.1; and many other burning tools. Burning Data DVDs The &man.growisofs.1; command is a frontend to mkisofs, it will invoke &man.mkisofs.8; to create the file system layout and will perform the write on the DVD. This means you do not need to create an image of the data before the burning process. To burn onto a DVD+R or a DVD-R the data from the /path/to/data directory, use the following command: &prompt.root; growisofs -dvd-compat -Z /dev/cd0 -J -R /path/to/data The options are passed to &man.mkisofs.8; for the file system creation (in this case: an ISO 9660 file system with Joliet and Rock Ridge extensions), consult the &man.mkisofs.8; manual page for more details. The option is used for the initial session recording in any case: multiple sessions or not. The DVD device, /dev/cd0, must be changed according to your configuration. The parameter will close the disk, the recording will be unappendable. In return this should provide better media compatibility with DVD-ROM drives. It is also possible to burn a pre-mastered image, for example to burn the image imagefile.iso, we will run: &prompt.root; growisofs -dvd-compat -Z /dev/cd0=imagefile.iso The write speed should be detected and automatically set according to the media and the drive being used. If you want to force the write speed, use the parameter. For more information, read the &man.growisofs.1; manual page. DVD DVD-Video Burning a DVD-Video A DVD-Video is a specific file layout based on ISO 9660 and the micro-UDF (M-UDF) specifications. The DVD-Video also presents a specific data structure hierarchy, it is the reason why you need a particular program such as multimedia/dvdauthor to author the DVD. If you already have an image of the DVD-Video file system, just burn it in the same way as for any image, see the previous section for an example. If you have made the DVD authoring and the result is in, for example, the directory /path/to/video, the following command should be used to burn the DVD-Video: &prompt.root; growisofs -Z /dev/cd0 -dvd-video /path/to/video The option will be passed down to &man.mkisofs.8; and will instruct it to create a DVD-Video file system layout. Beside this, the option implies &man.growisofs.1; option. DVD DVD+RW Using a DVD+RW Unlike CD-RW, a virgin DVD+RW needs to be formatted before first use. The &man.growisofs.1; program will take care of it automatically whenever appropriate, which is the recommended way. However you can use the dvd+rw-format command to format the DVD+RW: &prompt.root; dvd+rw-format /dev/cd0 You need to perform this operation just once, keep in mind that only virgin DVD+RW medias need to be formatted. Then you can burn the DVD+RW in the way seen in previous sections. If you want to burn new data (burn a totally new file system not append some data) onto a DVD+RW, you do not need to blank it, you just have to write over the previous recording (in performing a new initial session), like this: &prompt.root; growisofs -Z /dev/cd0 -J -R /path/to/newdata DVD+RW format offers the possibility to easily append data to a previous recording. The operation consists in merging a new session to the existing one, it is not multisession writing, &man.growisofs.1; will grow the ISO 9660 file system present on the media. For example, if we want to append data to our previous DVD+RW, we have to use the following: &prompt.root; growisofs -M /dev/cd0 -J -R /path/to/nextdata The same &man.mkisofs.8; options we used to burn the initial session should be used during next writes. You may want to use the option if you want better media compatibility with DVD-ROM drives. In the DVD+RW case, this will not prevent you from adding data. If for any reason you really want to blank the media, do the following: &prompt.root; growisofs -Z /dev/cd0=/dev/zero DVD DVD-RW Using a DVD-RW A DVD-RW accepts two disc formats: the incremental sequential one and the restricted overwrite. By default DVD-RW discs are in sequential format. A virgin DVD-RW can be directly written without the need of a formatting operation, however a non-virgin DVD-RW in sequential format needs to be blanked before to be able to write a new initial session. To blank a DVD-RW in sequential mode, run: &prompt.root; dvd+rw-format -blank=full /dev/cd0 A full blanking () will take about one hour on a 1x media. A fast blanking can be performed using the option if the DVD-RW will be recorded in Disk-At-Once (DAO) mode. To burn the DVD-RW in DAO mode, use the command: &prompt.root; growisofs -use-the-force-luke=dao -Z /dev/cd0=imagefile.iso The option should not be required since &man.growisofs.1; attempts to detect minimally (fast blanked) media and engage DAO write. In fact one should use restricted overwrite mode with any DVD-RW, this format is more flexible than the default incremental sequential one. To write data on a sequential DVD-RW, use the same instructions as for the other DVD formats: &prompt.root; growisofs -Z /dev/cd0 -J -R /path/to/data If you want to append some data to your previous recording, you will have to use the &man.growisofs.1; option. However, if you perform data addition on a DVD-RW in incremental sequential mode, a new session will be created on the disc and the result will be a multi-session disc. A DVD-RW in restricted overwrite format does not need to be blanked before a new initial session, you just have to overwrite the disc with the option, this is similar to the DVD+RW case. It is also possible to grow an existing ISO 9660 file system written on the disc in a same way as for a DVD+RW with the option. The result will be a one-session DVD. To put a DVD-RW in the restricted overwrite format, the following command must be used: &prompt.root; dvd+rw-format /dev/cd0 To change back to the sequential format use: &prompt.root; dvd+rw-format -blank=full /dev/cd0 Multisession Very few DVD-ROM drives support multisession DVDs, they will most of time, hopefully, only read the first session. DVD+R, DVD-R and DVD-RW in sequential format can accept multiple sessions, the notion of multiple sessions does not exist for the DVD+RW and the DVD-RW restricted overwrite formats. Using the following command after an initial (non-closed) session on a DVD+R, DVD-R, or DVD-RW in sequential format, will add a new session to the disc: &prompt.root; growisofs -M /dev/cd0 -J -R /path/to/nextdata Using this command line with a DVD+RW or a DVD-RW in restricted overwrite mode, will append data in merging the new session to the existing one. The result will be a single-session disc. This is the way used to add data after an initial write on these medias. Some space on the media is used between each session for end and start of sessions. Therefore, one should add sessions with large amount of data to optimize media space. The number of sessions is limited to 154 for a DVD+R, about 2000 for a DVD-R, and 127 for a DVD+R Double Layer. For More Information To obtain more information about a DVD, the dvd+rw-mediainfo /dev/cd0 command can be ran with the disc in the drive. More information about the dvd+rw-tools can be found in the &man.growisofs.1; manual page, on the dvd+rw-tools web site and in the cdwrite mailing list archives. The dvd+rw-mediainfo output of the resulting recording or the media with issues is mandatory for any problem report. Without this output, it will be quite impossible to help you. Using a DVD-RAM DVD DVD-RAM Configuration DVD-RAM writers come with either SCSI or ATAPI interface. DMA access for ATAPI devices has to be enabled, this can be done by adding the following line to the /boot/loader.conf file: hw.ata.atapi_dma="1" Preparing the Medium As previously mentioned in the chapter introduction, a DVD-RAM can be seen as a removable hard drive. As any other hard drive the DVD-RAM must be prepared before the first use. In the example, the whole disk space will be used with a standard UFS2 file system: &prompt.root; dd if=/dev/zero of=/dev/acd0 count=2 &prompt.root; bsdlabel -Bw acd0 &prompt.root; newfs /dev/acd0 The DVD device, acd0, must be changed according to the configuration. Using the Medium Once the previous operations have been performed on the DVD-RAM, it can be mounted as a normal hard drive: &prompt.root; mount /dev/acd0 /mnt After this the DVD-RAM will be both readable and writeable. Julio Merino Original work by Martin Karlsson Rewritten by Creating and Using Floppy Disks Storing data on floppy disks is sometimes useful, for example when one does not have any other removable storage media or when one needs to transfer small amounts of data to another computer. This section will explain how to use floppy disks in FreeBSD. It will primarily cover formatting and usage of 3.5inch DOS floppies, but the concepts are similar for other floppy disk formats. Formatting Floppies The Device Floppy disks are accessed through entries in /dev, just like other devices. To access the raw floppy disk, simply use /dev/fdN. Formatting A floppy disk needs to be low-level formated before it can be used. This is usually done by the vendor, but formatting is a good way to check media integrity. Although it is possible to force larger (or smaller) disk sizes, 1440kB is what most floppy disks are designed for. To low-level format the floppy disk you need to use &man.fdformat.1;. This utility expects the device name as an argument. Make note of any error messages, as these can help determine if the disk is good or bad. Formatting Floppy Disks Use the /dev/fdN devices to format the floppy. Insert a new 3.5inch floppy disk in your drive and issue: &prompt.root; /usr/sbin/fdformat -f 1440 /dev/fd0 The Disk Label After low-level formatting the disk, you will need to place a disk label on it. This disk label will be destroyed later, but it is needed by the system to determine the size of the disk and its geometry later. The new disk label will take over the whole disk, and will contain all the proper information about the geometry of the floppy. The geometry values for the disk label are listed in /etc/disktab. You can run now &man.bsdlabel.8; like so: &prompt.root; /sbin/bsdlabel -B -r -w /dev/fd0 fd1440 The File System Now the floppy is ready to be high-level formated. This will place a new file system on it, which will let FreeBSD read and write to the disk. After creating the new file system, the disk label is destroyed, so if you want to reformat the disk, you will have to recreate the disk label. The floppy's file system can be either UFS or FAT. FAT is generally a better choice for floppies. To put a new file system on the floppy, issue: &prompt.root; /sbin/newfs_msdos /dev/fd0 The disk is now ready for use. Using the Floppy To use the floppy, mount it with &man.mount.msdosfs.8;. One can also use emulators/mtools from the ports collection. Creating and Using Data Tapes tape media The major tape media are the 4mm, 8mm, QIC, mini-cartridge and DLT. 4mm (DDS: Digital Data Storage) tape media DDS (4mm) tapes tape media QIC tapes 4mm tapes are replacing QIC as the workstation backup media of choice. This trend accelerated greatly when Conner purchased Archive, a leading manufacturer of QIC drives, and then stopped production of QIC drives. 4mm drives are small and quiet but do not have the reputation for reliability that is enjoyed by 8mm drives. The cartridges are less expensive and smaller (3 x 2 x 0.5 inches, 76 x 51 x 12 mm) than 8mm cartridges. 4mm, like 8mm, has comparatively short head life for the same reason, both use helical scan. Data throughput on these drives starts ~150 kB/s, peaking at ~500 kB/s. Data capacity starts at 1.3 GB and ends at 2.0 GB. Hardware compression, available with most of these drives, approximately doubles the capacity. Multi-drive tape library units can have 6 drives in a single cabinet with automatic tape changing. Library capacities reach 240 GB. The DDS-3 standard now supports tape capacities up to 12 GB (or 24 GB compressed). 4mm drives, like 8mm drives, use helical-scan. All the benefits and drawbacks of helical-scan apply to both 4mm and 8mm drives. Tapes should be retired from use after 2,000 passes or 100 full backups. 8mm (Exabyte) tape media Exabyte (8mm) tapes 8mm tapes are the most common SCSI tape drives; they are the best choice of exchanging tapes. Nearly every site has an Exabyte 2 GB 8mm tape drive. 8mm drives are reliable, convenient and quiet. Cartridges are inexpensive and small (4.8 x 3.3 x 0.6 inches; 122 x 84 x 15 mm). One downside of 8mm tape is relatively short head and tape life due to the high rate of relative motion of the tape across the heads. Data throughput ranges from ~250 kB/s to ~500 kB/s. Data sizes start at 300 MB and go up to 7 GB. Hardware compression, available with most of these drives, approximately doubles the capacity. These drives are available as single units or multi-drive tape libraries with 6 drives and 120 tapes in a single cabinet. Tapes are changed automatically by the unit. Library capacities reach 840+ GB. The Exabyte Mammoth model supports 12 GB on one tape (24 GB with compression) and costs approximately twice as much as conventional tape drives. Data is recorded onto the tape using helical-scan, the heads are positioned at an angle to the media (approximately 6 degrees). The tape wraps around 270 degrees of the spool that holds the heads. The spool spins while the tape slides over the spool. The result is a high density of data and closely packed tracks that angle across the tape from one edge to the other. QIC tape media QIC-150 QIC-150 tapes and drives are, perhaps, the most common tape drive and media around. QIC tape drives are the least expensive serious backup drives. The downside is the cost of media. QIC tapes are expensive compared to 8mm or 4mm tapes, up to 5 times the price per GB data storage. But, if your needs can be satisfied with a half-dozen tapes, QIC may be the correct choice. QIC is the most common tape drive. Every site has a QIC drive of some density or another. Therein lies the rub, QIC has a large number of densities on physically similar (sometimes identical) tapes. QIC drives are not quiet. These drives audibly seek before they begin to record data and are clearly audible whenever reading, writing or seeking. QIC tapes measure 6 x 4 x 0.7 inches (152 x 102 x 17 mm). Data throughput ranges from ~150 kB/s to ~500 kB/s. Data capacity ranges from 40 MB to 15 GB. Hardware compression is available on many of the newer QIC drives. QIC drives are less frequently installed; they are being supplanted by DAT drives. Data is recorded onto the tape in tracks. The tracks run along the long axis of the tape media from one end to the other. The number of tracks, and therefore the width of a track, varies with the tape's capacity. Most if not all newer drives provide backward-compatibility at least for reading (but often also for writing). QIC has a good reputation regarding the safety of the data (the mechanics are simpler and more robust than for helical scan drives). Tapes should be retired from use after 5,000 backups. DLT tape media DLT DLT has the fastest data transfer rate of all the drive types listed here. The 1/2" (12.5mm) tape is contained in a single spool cartridge (4 x 4 x 1 inches; 100 x 100 x 25 mm). The cartridge has a swinging gate along one entire side of the cartridge. The drive mechanism opens this gate to extract the tape leader. The tape leader has an oval hole in it which the drive uses to hook the tape. The take-up spool is located inside the tape drive. All the other tape cartridges listed here (9 track tapes are the only exception) have both the supply and take-up spools located inside the tape cartridge itself. Data throughput is approximately 1.5 MB/s, three times the throughput of 4mm, 8mm, or QIC tape drives. Data capacities range from 10 GB to 20 GB for a single drive. Drives are available in both multi-tape changers and multi-tape, multi-drive tape libraries containing from 5 to 900 tapes over 1 to 20 drives, providing from 50 GB to 9 TB of storage. With compression, DLT Type IV format supports up to 70 GB capacity. Data is recorded onto the tape in tracks parallel to the direction of travel (just like QIC tapes). Two tracks are written at once. Read/write head lifetimes are relatively long; once the tape stops moving, there is no relative motion between the heads and the tape. AIT tape media AIT AIT is a new format from Sony, and can hold up to 50 GB (with compression) per tape. The tapes contain memory chips which retain an index of the tape's contents. This index can be rapidly read by the tape drive to determine the position of files on the tape, instead of the several minutes that would be required for other tapes. Software such as SAMS:Alexandria can operate forty or more AIT tape libraries, communicating directly with the tape's memory chip to display the contents on screen, determine what files were backed up to which tape, locate the correct tape, load it, and restore the data from the tape. Libraries like this cost in the region of $20,000, pricing them a little out of the hobbyist market. Using a New Tape for the First Time The first time that you try to read or write a new, completely blank tape, the operation will fail. The console messages should be similar to: sa0(ncr1:4:0): NOT READY asc:4,1 sa0(ncr1:4:0): Logical unit is in process of becoming ready The tape does not contain an Identifier Block (block number 0). All QIC tape drives since the adoption of QIC-525 standard write an Identifier Block to the tape. There are two solutions: mt fsf 1 causes the tape drive to write an Identifier Block to the tape. Use the front panel button to eject the tape. Re-insert the tape and dump data to the tape. dump will report DUMP: End of tape detected and the console will show: HARDWARE FAILURE info:280 asc:80,96. rewind the tape using: mt rewind. Subsequent tape operations are successful. Backups to Floppies Can I Use Floppies for Backing Up My Data? backup floppies floppy disks Floppy disks are not really a suitable media for making backups as: The media is unreliable, especially over long periods of time. Backing up and restoring is very slow. They have a very limited capacity (the days of backing up an entire hard disk onto a dozen or so floppies has long since passed). However, if you have no other method of backing up your data then floppy disks are better than no backup at all. If you do have to use floppy disks then ensure that you use good quality ones. Floppies that have been lying around the office for a couple of years are a bad choice. Ideally use new ones from a reputable manufacturer. So How Do I Backup My Data to Floppies? The best way to backup to floppy disk is to use &man.tar.1; with the (multi volume) option, which allows backups to span multiple floppies. To backup all the files in the current directory and sub-directory use this (as root): &prompt.root; tar Mcvf /dev/fd0 * When the first floppy is full &man.tar.1; will prompt you to insert the next volume (because &man.tar.1; is media independent it refers to volumes; in this context it means floppy disk). Prepare volume #2 for /dev/fd0 and hit return: This is repeated (with the volume number incrementing) until all the specified files have been archived. Can I Compress My Backups? tar gzip compression Unfortunately, &man.tar.1; will not allow the option to be used for multi-volume archives. You could, of course, &man.gzip.1; all the files, &man.tar.1; them to the floppies, then &man.gunzip.1; the files again! How Do I Restore My Backups? To restore the entire archive use: &prompt.root; tar Mxvf /dev/fd0 There are two ways that you can use to restore only specific files. First, you can start with the first floppy and use: &prompt.root; tar Mxvf /dev/fd0 filename The utility &man.tar.1; will prompt you to insert subsequent floppies until it finds the required file. Alternatively, if you know which floppy the file is on then you can simply insert that floppy and use the same command as above. Note that if the first file on the floppy is a continuation from the previous one then &man.tar.1; will warn you that it cannot restore it, even if you have not asked it to! Lowell Gilbert Original work by Backup Strategies The first requirement in devising a backup plan is to make sure that all of the following problems are covered: Disk failure Accidental file deletion Random file corruption Complete machine destruction (e.g. fire), including destruction of any on-site backups. It is perfectly possible that some systems will be best served by having each of these problems covered by a completely different technique. Except for strictly personal systems with very low-value data, it is unlikely that one technique would cover all of them. Some of the techniques in the toolbox are: Archives of the whole system, backed up onto permanent media offsite. This actually provides protection against all of the possible problems listed above, but is slow and inconvenient to restore from. You can keep copies of the backups onsite and/or online, but there will still be inconveniences in restoring files, especially for non-privileged users. Filesystem snapshots. This is really only helpful in the accidental file deletion scenario, but it can be very helpful in that case, and is quick and easy to deal with. Copies of whole filesystems and/or disks (e.g. periodic &man.rsync.1; of the whole machine). This is generally most useful in networks with unique requirements. For general protection against disk failure, it is usually inferior to RAID. For restoring accidentally deleted files, it can be comparable to UFS snapshots, but that depends on your preferences. RAID. Minimizes or avoids downtime when a disk fails. At the expense of having to deal with disk failures more often (because you have more disks), albeit at a much lower urgency. Checking fingerprints of files. The &man.mtree.8; utility is very useful for this. Although it is not a backup technique, it helps guarantee that you will notice when you need to resort to your backups. This is particularly important for offline backups, and should be checked periodically. It is quite easy to come up with even more techniques, many of them variations on the ones listed above. Specialized requirements will usually lead to specialized techniques (for example, backing up a live database usually requires a method particular to the database software as an intermediate step). The important thing is to know what dangers you want to protect against, and how you will handle each. Backup Basics The three major backup programs are &man.dump.8;, &man.tar.1;, and &man.cpio.1;. Dump and Restore backup software dump / restore dump restore The traditional &unix; backup programs are dump and restore. They operate on the drive as a collection of disk blocks, below the abstractions of files, links and directories that are created by the file systems. dump backs up an entire file system on a device. It is unable to backup only part of a file system or a directory tree that spans more than one file system. dump does not write files and directories to tape, but rather writes the raw data blocks that comprise files and directories. If you use dump on your root directory, you would not back up /home, /usr or many other directories since these are typically mount points for other file systems or symbolic links into those file systems. dump has quirks that remain from its early days in Version 6 of AT&T UNIX (circa 1975). The default parameters are suitable for 9-track tapes (6250 bpi), not the high-density media available today (up to 62,182 ftpi). These defaults must be overridden on the command line to utilize the capacity of current tape drives. .rhosts It is also possible to backup data across the network to a tape drive attached to another computer with rdump and rrestore. Both programs rely upon &man.rcmd.3; and &man.ruserok.3; to access the remote tape drive. Therefore, the user performing the backup must be listed in the .rhosts file on the remote computer. The arguments to rdump and rrestore must be suitable to use on the remote computer. When rdumping from a FreeBSD computer to an Exabyte tape drive connected to a Sun called komodo, use: &prompt.root; /sbin/rdump 0dsbfu 54000 13000 126 komodo:/dev/nsa8 /dev/da0a 2>&1 Beware: there are security implications to allowing .rhosts authentication. Evaluate your situation carefully. It is also possible to use dump and restore in a more secure fashion over ssh. Using <command>dump</command> over <application>ssh</application> &prompt.root; /sbin/dump -0uan -f - /usr | gzip -2 | ssh -c blowfish \ targetuser@targetmachine.example.com dd of=/mybigfiles/dump-usr-l0.gz Or using dump's built-in method, setting the environment variable RSH: Using <command>dump</command> over <application>ssh</application> with <envar>RSH</envar> set &prompt.root; RSH=/usr/bin/ssh /sbin/dump -0uan -f targetuser@targetmachine.example.com:/dev/sa0 /usr <command>tar</command> backup software tar &man.tar.1; also dates back to Version 6 of AT&T UNIX (circa 1975). tar operates in cooperation with the file system; it writes files and directories to tape. tar does not support the full range of options that are available from &man.cpio.1;, but it does not require the unusual command pipeline that cpio uses. tar On FreeBSD 5.3 and later, both GNU tar and the default bsdtar are available. The GNU version can be invoked with gtar. It supports remote devices using the same syntax as rdump. To tar to an Exabyte tape drive connected to a Sun called komodo, use: &prompt.root; /usr/bin/gtar cf komodo:/dev/nsa8 . 2>&1 The same could be accomplished with bsdtar by using a pipeline and rsh to send the data to a remote tape drive. &prompt.root; tar cf - . | rsh hostname dd of=tape-device obs=20b If you are worried about the security of backing up over a network you should use the ssh command instead of rsh. <command>cpio</command> backup software cpio &man.cpio.1; is the original &unix; file interchange tape program for magnetic media. cpio has options (among many others) to perform byte-swapping, write a number of different archive formats, and pipe the data to other programs. This last feature makes cpio an excellent choice for installation media. cpio does not know how to walk the directory tree and a list of files must be provided through stdin. cpio cpio does not support backups across the network. You can use a pipeline and rsh to send the data to a remote tape drive. &prompt.root; for f in directory_list; do find $f >> backup.list done &prompt.root; cpio -v -o --format=newc < backup.list | ssh user@host "cat > backup_device" Where directory_list is the list of directories you want to back up, user@host is the user/hostname combination that will be performing the backups, and backup_device is where the backups should be written to (e.g., /dev/nsa0). <command>pax</command> backup software pax pax POSIX IEEE &man.pax.1; is IEEE/&posix;'s answer to tar and cpio. Over the years the various versions of tar and cpio have gotten slightly incompatible. So rather than fight it out to fully standardize them, &posix; created a new archive utility. pax attempts to read and write many of the various cpio and tar formats, plus new formats of its own. Its command set more resembles cpio than tar. <application>Amanda</application> backup software Amanda Amanda Amanda (Advanced Maryland Network Disk Archiver) is a client/server backup system, rather than a single program. An Amanda server will backup to a single tape drive any number of computers that have Amanda clients and a network connection to the Amanda server. A common problem at sites with a number of large disks is that the length of time required to backup to data directly to tape exceeds the amount of time available for the task. Amanda solves this problem. Amanda can use a holding disk to backup several file systems at the same time. Amanda creates archive sets: a group of tapes used over a period of time to create full backups of all the file systems listed in Amanda's configuration file. The archive set also contains nightly incremental (or differential) backups of all the file systems. Restoring a damaged file system requires the most recent full backup and the incremental backups. The configuration file provides fine control of backups and the network traffic that Amanda generates. Amanda will use any of the above backup programs to write the data to tape. Amanda is available as either a port or a package, it is not installed by default. Do Nothing Do nothing is not a computer program, but it is the most widely used backup strategy. There are no initial costs. There is no backup schedule to follow. Just say no. If something happens to your data, grin and bear it! If your time and your data is worth little to nothing, then Do nothing is the most suitable backup program for your computer. But beware, &unix; is a useful tool, you may find that within six months you have a collection of files that are valuable to you. Do nothing is the correct backup method for /usr/obj and other directory trees that can be exactly recreated by your computer. An example is the files that comprise the HTML or &postscript; version of this Handbook. These document formats have been created from SGML input files. Creating backups of the HTML or &postscript; files is not necessary. The SGML files are backed up regularly. Which Backup Program Is Best? LISA &man.dump.8; Period. Elizabeth D. Zwicky torture tested all the backup programs discussed here. The clear choice for preserving all your data and all the peculiarities of &unix; file systems is dump. Elizabeth created file systems containing a large variety of unusual conditions (and some not so unusual ones) and tested each program by doing a backup and restore of those file systems. The peculiarities included: files with holes, files with holes and a block of nulls, files with funny characters in their names, unreadable and unwritable files, devices, files that change size during the backup, files that are created/deleted during the backup and more. She presented the results at LISA V in Oct. 1991. See torture-testing Backup and Archive Programs. Emergency Restore Procedure Before the Disaster There are only four steps that you need to perform in preparation for any disaster that may occur. bsdlabel First, print the bsdlabel from each of your disks (e.g. bsdlabel da0 | lpr), your file system table (/etc/fstab) and all boot messages, two copies of each. fix-it floppies Second, determine that the boot and fix-it floppies (boot.flp and fixit.flp) have all your devices. The easiest way to check is to reboot your machine with the boot floppy in the floppy drive and check the boot messages. If all your devices are listed and functional, skip on to step three. Otherwise, you have to create two custom bootable floppies which have a kernel that can mount all of your disks and access your tape drive. These floppies must contain: fdisk, bsdlabel, newfs, mount, and whichever backup program you use. These programs must be statically linked. If you use dump, the floppy must contain restore. Third, create backup tapes regularly. Any changes that you make after your last backup may be irretrievably lost. Write-protect the backup tapes. Fourth, test the floppies (either boot.flp and fixit.flp or the two custom bootable floppies you made in step two.) and backup tapes. Make notes of the procedure. Store these notes with the bootable floppy, the printouts and the backup tapes. You will be so distraught when restoring that the notes may prevent you from destroying your backup tapes (How? In place of tar xvf /dev/sa0, you might accidentally type tar cvf /dev/sa0 and over-write your backup tape). For an added measure of security, make bootable floppies and two backup tapes each time. Store one of each at a remote location. A remote location is NOT the basement of the same office building. A number of firms in the World Trade Center learned this lesson the hard way. A remote location should be physically separated from your computers and disk drives by a significant distance. A Script for Creating a Bootable Floppy /mnt/sbin/init gzip -c -best /sbin/fsck > /mnt/sbin/fsck gzip -c -best /sbin/mount > /mnt/sbin/mount gzip -c -best /sbin/halt > /mnt/sbin/halt gzip -c -best /sbin/restore > /mnt/sbin/restore gzip -c -best /bin/sh > /mnt/bin/sh gzip -c -best /bin/sync > /mnt/bin/sync cp /root/.profile /mnt/root cp -f /dev/MAKEDEV /mnt/dev chmod 755 /mnt/dev/MAKEDEV chmod 500 /mnt/sbin/init chmod 555 /mnt/sbin/fsck /mnt/sbin/mount /mnt/sbin/halt chmod 555 /mnt/bin/sh /mnt/bin/sync chmod 6555 /mnt/sbin/restore # # create the devices nodes # cd /mnt/dev ./MAKEDEV std ./MAKEDEV da0 ./MAKEDEV da1 ./MAKEDEV da2 ./MAKEDEV sa0 ./MAKEDEV pty0 cd / # # create minimum file system table # cat > /mnt/etc/fstab < /mnt/etc/passwd < /mnt/etc/master.passwd < After the Disaster The key question is: did your hardware survive? You have been doing regular backups so there is no need to worry about the software. If the hardware has been damaged, the parts should be replaced before attempting to use the computer. If your hardware is okay, check your floppies. If you are using a custom boot floppy, boot single-user (type -s at the boot: prompt). Skip the following paragraph. If you are using the boot.flp and fixit.flp floppies, keep reading. Insert the boot.flp floppy in the first floppy drive and boot the computer. The original install menu will be displayed on the screen. Select the Fixit--Repair mode with CDROM or floppy. option. Insert the fixit.flp when prompted. restore and the other programs that you need are located in /mnt2/rescue (/mnt2/stand for &os; versions older than 5.2). Recover each file system separately. mount root partition bsdlabel newfs Try to mount (e.g. mount /dev/da0a /mnt) the root partition of your first disk. If the bsdlabel was damaged, use bsdlabel to re-partition and label the disk to match the label that you printed and saved. Use newfs to re-create the file systems. Re-mount the root partition of the floppy read-write (mount -u -o rw /mnt). Use your backup program and backup tapes to recover the data for this file system (e.g. restore vrf /dev/sa0). Unmount the file system (e.g. umount /mnt). Repeat for each file system that was damaged. Once your system is running, backup your data onto new tapes. Whatever caused the crash or data loss may strike again. Another hour spent now may save you from further distress later. * I Did Not Prepare for the Disaster, What Now? ]]> Marc Fonvieille Reorganized and enhanced by Network, Memory, and File-Backed File Systems virtual disks disks virtual Aside from the disks you physically insert into your computer: floppies, CDs, hard drives, and so forth; other forms of disks are understood by FreeBSD - the virtual disks. NFS Coda disks memory These include network file systems such as the Network File System and Coda, memory-based file systems and file-backed file systems. According to the FreeBSD version you run, you will have to use different tools for creation and use of file-backed and memory-based file systems. Use &man.devfs.5; to allocate device nodes transparently for the user. File-Backed File System disks file-backed The utility &man.mdconfig.8; is used to configure and enable memory disks, &man.md.4;, under FreeBSD. To use &man.mdconfig.8;, you have to load &man.md.4; module or to add the support in your kernel configuration file: device md The &man.mdconfig.8; command supports three kinds of memory backed virtual disks: memory disks allocated with &man.malloc.9;, memory disks using a file or swap space as backing. One possible use is the mounting of floppy or CD images kept in files. To mount an existing file system image: Using <command>mdconfig</command> to Mount an Existing File System Image &prompt.root; mdconfig -a -t vnode -f diskimage -u 0 &prompt.root; mount /dev/md0 /mnt To create a new file system image with &man.mdconfig.8;: Creating a New File-Backed Disk with <command>mdconfig</command> &prompt.root; dd if=/dev/zero of=newimage bs=1k count=5k 5120+0 records in 5120+0 records out &prompt.root; mdconfig -a -t vnode -f newimage -u 0 &prompt.root; bsdlabel -w md0 auto &prompt.root; newfs md0a /dev/md0a: 5.0MB (10224 sectors) block size 16384, fragment size 2048 using 4 cylinder groups of 1.25MB, 80 blks, 192 inodes. super-block backups (for fsck -b #) at: 160, 2720, 5280, 7840 &prompt.root; mount /dev/md0a /mnt &prompt.root; df /mnt Filesystem 1K-blocks Used Avail Capacity Mounted on /dev/md0a 4710 4 4330 0% /mnt If you do not specify the unit number with the option, &man.mdconfig.8; will use the &man.md.4; automatic allocation to select an unused device. The name of the allocated unit will be output on stdout like md4. For more details about &man.mdconfig.8;, please refer to the manual page. The utility &man.mdconfig.8; is very useful, however it asks many command lines to create a file-backed file system. FreeBSD also comes with a tool called &man.mdmfs.8;, this program configures a &man.md.4; disk using &man.mdconfig.8;, puts a UFS file system on it using &man.newfs.8;, and mounts it using &man.mount.8;. For example, if you want to create and mount the same file system image as above, simply type the following: Configure and Mount a File-Backed Disk with <command>mdmfs</command> &prompt.root; dd if=/dev/zero of=newimage bs=1k count=5k 5120+0 records in 5120+0 records out &prompt.root; mdmfs -F newimage -s 5m md0 /mnt &prompt.root; df /mnt Filesystem 1K-blocks Used Avail Capacity Mounted on /dev/md0 4718 4 4338 0% /mnt If you use the option without unit number, &man.mdmfs.8; will use &man.md.4; auto-unit feature to automatically select an unused device. For more details about &man.mdmfs.8;, please refer to the manual page. Memory-Based File System disks memory file system For a memory-based file system the swap backing should normally be used. Using swap backing does not mean that the memory disk will be swapped out to disk by default, but merely that the memory disk will be allocated from a memory pool which can be swapped out to disk if needed. It is also possible to create memory-based disk which are &man.malloc.9; backed, but using malloc backed memory disks, especially large ones, can result in a system panic if the kernel runs out of memory. Creating a New Memory-Based Disk with <command>mdconfig</command> &prompt.root; mdconfig -a -t swap -s 5m -u 1 &prompt.root; newfs -U md1 /dev/md1: 5.0MB (10240 sectors) block size 16384, fragment size 2048 using 4 cylinder groups of 1.27MB, 81 blks, 192 inodes. with soft updates super-block backups (for fsck -b #) at: 160, 2752, 5344, 7936 &prompt.root; mount /dev/md1 /mnt &prompt.root; df /mnt Filesystem 1K-blocks Used Avail Capacity Mounted on /dev/md1 4718 4 4338 0% /mnt Creating a New Memory-Based Disk with <command>mdmfs</command> &prompt.root; mdmfs -s 5m md2 /mnt &prompt.root; df /mnt Filesystem 1K-blocks Used Avail Capacity Mounted on /dev/md2 4846 2 4458 0% /mnt Detaching a Memory Disk from the System disks detaching a memory disk When a memory-based or file-based file system is not used, you should release all resources to the system. The first thing to do is to unmount the file system, then use &man.mdconfig.8; to detach the disk from the system and release the resources. For example to detach and free all resources used by /dev/md4: &prompt.root; mdconfig -d -u 4 It is possible to list information about configured &man.md.4; devices in using the command mdconfig -l. Tom Rhodes Contributed by File System Snapshots file systems snapshots FreeBSD offers a feature in conjunction with Soft Updates: File system snapshots. Snapshots allow a user to create images of specified file systems, and treat them as a file. Snapshot files must be created in the file system that the action is performed on, and a user may create no more than 20 snapshots per file system. Active snapshots are recorded in the superblock so they are persistent across unmount and remount operations along with system reboots. When a snapshot is no longer required, it can be removed with the standard &man.rm.1; command. Snapshots may be removed in any order, however all the used space may not be acquired because another snapshot will possibly claim some of the released blocks. The un-alterable file flag is set by &man.mksnap.ffs.8; after initial creation of a snapshot file. The &man.unlink.1; command makes an exception for snapshot files since it allows them to be removed. Snapshots are created with the &man.mount.8; command. To place a snapshot of /var in the file /var/snapshot/snap use the following command: &prompt.root; mount -u -o snapshot /var/snapshot/snap /var Alternatively, you can use &man.mksnap.ffs.8; to create a snapshot: &prompt.root; mksnap_ffs /var /var/snapshot/snap One can find snapshot files on a file system (e.g. /var) by using the &man.find.1; command: &prompt.root; find /var -flags snapshot Once a snapshot has been created, it has several uses: Some administrators will use a snapshot file for backup purposes, because the snapshot can be transfered to CDs or tape. The file system integrity checker, &man.fsck.8;, may be run on the snapshot. Assuming that the file system was clean when it was mounted, you should always get a clean (and unchanging) result. This is essentially what the background &man.fsck.8; process does. Run the &man.dump.8; utility on the snapshot. A dump will be returned that is consistent with the file system and the timestamp of the snapshot. &man.dump.8; can also take a snapshot, create a dump image and then remove the snapshot in one command using the flag. &man.mount.8; the snapshot as a frozen image of the file system. To &man.mount.8; the snapshot /var/snapshot/snap run: &prompt.root; mdconfig -a -t vnode -f /var/snapshot/snap -u 4 &prompt.root; mount -r /dev/md4 /mnt You can now walk the hierarchy of your frozen /var file system mounted at /mnt. Everything will initially be in the same state it was during the snapshot creation time. The only exception is that any earlier snapshots will appear as zero length files. When the use of a snapshot has delimited, it can be unmounted with: &prompt.root; umount /mnt &prompt.root; mdconfig -d -u 4 For more information about and file system snapshots, including technical papers, you can visit Marshall Kirk McKusick's website at . File System Quotas accounting disk space disk quotas Quotas are an optional feature of the operating system that allow you to limit the amount of disk space and/or the number of files a user or members of a group may allocate on a per-file system basis. This is used most often on timesharing systems where it is desirable to limit the amount of resources any one user or group of users may allocate. This will prevent one user or group of users from consuming all of the available disk space. Configuring Your System to Enable Disk Quotas Before attempting to use disk quotas, it is necessary to make sure that quotas are configured in your kernel. This is done by adding the following line to your kernel configuration file: options QUOTA The stock GENERIC kernel does not have this enabled by default, so you will have to configure, build and install a custom kernel in order to use disk quotas. Please refer to for more information on kernel configuration. Next you will need to enable disk quotas in /etc/rc.conf. This is done by adding the line: enable_quotas="YES" disk quotas checking For finer control over your quota startup, there is an additional configuration variable available. Normally on bootup, the quota integrity of each file system is checked by the &man.quotacheck.8; program. The &man.quotacheck.8; facility insures that the data in the quota database properly reflects the data on the file system. This is a very time consuming process that will significantly affect the time your system takes to boot. If you would like to skip this step, a variable in /etc/rc.conf is made available for the purpose: check_quotas="NO" Finally you will need to edit /etc/fstab to enable disk quotas on a per-file system basis. This is where you can either enable user or group quotas or both for all of your file systems. To enable per-user quotas on a file system, add the option to the options field in the /etc/fstab entry for the file system you want to enable quotas on. For example: /dev/da1s2g /home ufs rw,userquota 1 2 Similarly, to enable group quotas, use the option instead of . To enable both user and group quotas, change the entry as follows: /dev/da1s2g /home ufs rw,userquota,groupquota 1 2 By default, the quota files are stored in the root directory of the file system with the names quota.user and quota.group for user and group quotas respectively. See &man.fstab.5; for more information. Even though the &man.fstab.5; manual page says that you can specify an alternate location for the quota files, this is not recommended because the various quota utilities do not seem to handle this properly. At this point you should reboot your system with your new kernel. /etc/rc will automatically run the appropriate commands to create the initial quota files for all of the quotas you enabled in /etc/fstab, so there is no need to manually create any zero length quota files. In the normal course of operations you should not be required to run the &man.quotacheck.8;, &man.quotaon.8;, or &man.quotaoff.8; commands manually. However, you may want to read their manual pages just to be familiar with their operation. Setting Quota Limits disk quotas limits Once you have configured your system to enable quotas, verify that they really are enabled. An easy way to do this is to run: &prompt.root; quota -v You should see a one line summary of disk usage and current quota limits for each file system that quotas are enabled on. You are now ready to start assigning quota limits with the &man.edquota.8; command. You have several options on how to enforce limits on the amount of disk space a user or group may allocate, and how many files they may create. You may limit allocations based on disk space (block quotas) or number of files (inode quotas) or a combination of both. Each of these limits are further broken down into two categories: hard and soft limits. hard limit A hard limit may not be exceeded. Once a user reaches his hard limit he may not make any further allocations on the file system in question. For example, if the user has a hard limit of 500 kbytes on a file system and is currently using 490 kbytes, the user can only allocate an additional 10 kbytes. Attempting to allocate an additional 11 kbytes will fail. soft limit Soft limits, on the other hand, can be exceeded for a limited amount of time. This period of time is known as the grace period, which is one week by default. If a user stays over his or her soft limit longer than the grace period, the soft limit will turn into a hard limit and no further allocations will be allowed. When the user drops back below the soft limit, the grace period will be reset. The following is an example of what you might see when you run the &man.edquota.8; command. When the &man.edquota.8; command is invoked, you are placed into the editor specified by the EDITOR environment variable, or in the vi editor if the EDITOR variable is not set, to allow you to edit the quota limits. &prompt.root; edquota -u test Quotas for user test: /usr: kbytes in use: 65, limits (soft = 50, hard = 75) inodes in use: 7, limits (soft = 50, hard = 60) /usr/var: kbytes in use: 0, limits (soft = 50, hard = 75) inodes in use: 0, limits (soft = 50, hard = 60) You will normally see two lines for each file system that has quotas enabled. One line for the block limits, and one line for inode limits. Simply change the value you want updated to modify the quota limit. For example, to raise this user's block limit from a soft limit of 50 and a hard limit of 75 to a soft limit of 500 and a hard limit of 600, change: /usr: kbytes in use: 65, limits (soft = 50, hard = 75) to: /usr: kbytes in use: 65, limits (soft = 500, hard = 600) The new quota limits will be in place when you exit the editor. Sometimes it is desirable to set quota limits on a range of UIDs. This can be done by use of the option on the &man.edquota.8; command. First, assign the desired quota limit to a user, and then run edquota -p protouser startuid-enduid. For example, if user test has the desired quota limits, the following command can be used to duplicate those quota limits for UIDs 10,000 through 19,999: &prompt.root; edquota -p test 10000-19999 For more information see &man.edquota.8; manual page. Checking Quota Limits and Disk Usage disk quotas checking You can use either the &man.quota.1; or the &man.repquota.8; commands to check quota limits and disk usage. The &man.quota.1; command can be used to check individual user or group quotas and disk usage. A user may only examine his own quota, and the quota of a group he is a member of. Only the super-user may view all user and group quotas. The &man.repquota.8; command can be used to get a summary of all quotas and disk usage for file systems with quotas enabled. The following is some sample output from the quota -v command for a user that has quota limits on two file systems. Disk quotas for user test (uid 1002): Filesystem usage quota limit grace files quota limit grace /usr 65* 50 75 5days 7 50 60 /usr/var 0 50 75 0 50 60 grace period On the /usr file system in the above example, this user is currently 15 kbytes over the soft limit of 50 kbytes and has 5 days of the grace period left. Note the asterisk * which indicates that the user is currently over his quota limit. Normally file systems that the user is not using any disk space on will not show up in the output from the &man.quota.1; command, even if he has a quota limit assigned for that file system. The option will display those file systems, such as the /usr/var file system in the above example. Quotas over NFS NFS Quotas are enforced by the quota subsystem on the NFS server. The &man.rpc.rquotad.8; daemon makes quota information available to the &man.quota.1; command on NFS clients, allowing users on those machines to see their quota statistics. Enable rpc.rquotad in /etc/inetd.conf like so: rquotad/1 dgram rpc/udp wait root /usr/libexec/rpc.rquotad rpc.rquotad Now restart inetd: &prompt.root; kill -HUP `cat /var/run/inetd.pid` Lucky Green Contributed by
shamrock@cypherpunks.to
 Encrypting Disk Partitions disks encrypting FreeBSD offers excellent online protections against unauthorized data access. File permissions and Mandatory Access Control (MAC) (see ) help prevent unauthorized third-parties from accessing data while the operating system is active and the computer is powered up. However, the permissions enforced by the operating system are irrelevant if an attacker has physical access to a computer and can simply move the computer's hard drive to another system to copy and analyze the sensitive data. Regardless of how an attacker may have come into possession of a hard drive or powered-down computer, both GEOM Based Disk Encryption (gbde) and geli cryptographic subsystems in &os; are able to protect the data on the computer's file systems against even highly-motivated attackers with significant resources. Unlike cumbersome encryption methods that encrypt only individual files, gbde and geli transparently encrypt entire file systems. No cleartext ever touches the hard drive's platter. Disk Encryption with <application>gbde</application> Become <username>root</username> Configuring gbde requires super-user privileges. &prompt.user; su - Password: Add &man.gbde.4; Support to the Kernel Configuration File Add the following line to the kernel configuration file: options GEOM_BDE Rebuild the kernel as described in . Reboot into the new kernel. An alternative to recompiling the kernel is to use kldload to load &man.gbde.4;: &prompt.root; kldload geom_bde At this time there is no option in /boot/loader.conf to load the kernel module at boot time. Preparing the Encrypted Hard Drive The following example assumes that you are adding a new hard drive to your system that will hold a single encrypted partition. This partition will be mounted as /private. gbde can also be used to encrypt /home and /var/mail, but this requires more complex instructions which exceed the scope of this introduction. Add the New Hard Drive Install the new drive to the system as explained in . For the purposes of this example, a new hard drive partition has been added as /dev/ad4s1c. The /dev/ad0s1* devices represent existing standard FreeBSD partitions on the example system. &prompt.root; ls /dev/ad* /dev/ad0 /dev/ad0s1b /dev/ad0s1e /dev/ad4s1 /dev/ad0s1 /dev/ad0s1c /dev/ad0s1f /dev/ad4s1c /dev/ad0s1a /dev/ad0s1d /dev/ad4 Create a Directory to Hold gbde Lock Files &prompt.root; mkdir /etc/gbde The gbde lock file contains information that gbde requires to access encrypted partitions. Without access to the lock file, gbde will not be able to decrypt the data contained in the encrypted partition without significant manual intervention which is not supported by the software. Each encrypted partition uses a separate lock file. Initialize the gbde Partition A gbde partition must be initialized before it can be used. This initialization needs to be performed only once: &prompt.root; gbde init /dev/ad4s1c -i -L /etc/gbde/ad4s1c &man.gbde.8; will open your editor, permitting you to set various configuration options in a template. For use with UFS1 or UFS2, set the sector_size to 2048: $FreeBSD: src/sbin/gbde/template.txt,v 1.1 2002/10/20 11:16:13 phk Exp $ # # Sector size is the smallest unit of data which can be read or written. # Making it too small decreases performance and decreases available space. # Making it too large may prevent filesystems from working. 512 is the # minimum and always safe. For UFS, use the fragment size # sector_size = 2048 [...] &man.gbde.8; will ask you twice to type the passphrase that should be used to secure the data. The passphrase must be the same both times. gbde's ability to protect your data depends entirely on the quality of the passphrase that you choose. For tips on how to select a secure passphrase that is easy to remember, see the Diceware Passphrase website. The gbde init command creates a lock file for your gbde partition that in this example is stored as /etc/gbde/ad4s1c. gbde lock files must be backed up together with the contents of any encrypted partitions. While deleting a lock file alone cannot prevent a determined attacker from decrypting a gbde partition, without the lock file, the legitimate owner will be unable to access the data on the encrypted partition without a significant amount of work that is totally unsupported by &man.gbde.8; and its designer. Attach the Encrypted Partition to the Kernel &prompt.root; gbde attach /dev/ad4s1c -l /etc/gbde/ad4s1c You will be asked to provide the passphrase that you selected during the initialization of the encrypted partition. The new encrypted device will show up in /dev as /dev/device_name.bde: &prompt.root; ls /dev/ad* /dev/ad0 /dev/ad0s1b /dev/ad0s1e /dev/ad4s1 /dev/ad0s1 /dev/ad0s1c /dev/ad0s1f /dev/ad4s1c /dev/ad0s1a /dev/ad0s1d /dev/ad4 /dev/ad4s1c.bde Create a File System on the Encrypted Device Once the encrypted device has been attached to the kernel, you can create a file system on the device. To create a file system on the encrypted device, use &man.newfs.8;. Since it is much faster to initialize a new UFS2 file system than it is to initialize the old UFS1 file system, using &man.newfs.8; with the option is recommended. &prompt.root; newfs -U -O2 /dev/ad4s1c.bde The &man.newfs.8; command must be performed on an attached gbde partition which is identified by a *.bde extension to the device name. Mount the Encrypted Partition Create a mount point for the encrypted file system. &prompt.root; mkdir /private Mount the encrypted file system. &prompt.root; mount /dev/ad4s1c.bde /private Verify That the Encrypted File System is Available The encrypted file system should now be visible to &man.df.1; and be available for use. &prompt.user; df -H Filesystem Size Used Avail Capacity Mounted on /dev/ad0s1a 1037M 72M 883M 8% / /devfs 1.0K 1.0K 0B 100% /dev /dev/ad0s1f 8.1G 55K 7.5G 0% /home /dev/ad0s1e 1037M 1.1M 953M 0% /tmp /dev/ad0s1d 6.1G 1.9G 3.7G 35% /usr /dev/ad4s1c.bde 150G 4.1K 138G 0% /private Mounting Existing Encrypted File Systems After each boot, any encrypted file systems must be re-attached to the kernel, checked for errors, and mounted, before the file systems can be used. The required commands must be executed as user root. Attach the gbde Partition to the Kernel &prompt.root; gbde attach /dev/ad4s1c -l /etc/gbde/ad4s1c You will be asked to provide the passphrase that you selected during initialization of the encrypted gbde partition. Check the File System for Errors Since encrypted file systems cannot yet be listed in /etc/fstab for automatic mounting, the file systems must be checked for errors by running &man.fsck.8; manually before mounting. &prompt.root; fsck -p -t ffs /dev/ad4s1c.bde Mount the Encrypted File System &prompt.root; mount /dev/ad4s1c.bde /private The encrypted file system is now available for use. Automatically Mounting Encrypted Partitions It is possible to create a script to automatically attach, check, and mount an encrypted partition, but for security reasons the script should not contain the &man.gbde.8; password. Instead, it is recommended that such scripts be run manually while providing the password via the console or &man.ssh.1;. As an alternative, an rc.d script is provided. Arguments for this script can be passed via &man.rc.conf.5;, for example: gbde_autoattach_all="YES" gbde_devices="ad4s1c" This will require that the gbde passphrase be entered at boot time. After typing the correct passphrase, the gbde encrypted partition will be mounted automatically. This can be very useful when using gbde on notebooks. Cryptographic Protections Employed by gbde &man.gbde.8; encrypts the sector payload using 128-bit AES in CBC mode. Each sector on the disk is encrypted with a different AES key. For more information on gbde's cryptographic design, including how the sector keys are derived from the user-supplied passphrase, see &man.gbde.4;. Compatibility Issues &man.sysinstall.8; is incompatible with gbde-encrypted devices. All *.bde devices must be detached from the kernel before starting &man.sysinstall.8; or it will crash during its initial probing for devices. To detach the encrypted device used in our example, use the following command: &prompt.root; gbde detach /dev/ad4s1c Also note that, as &man.vinum.4; does not use the &man.geom.4; subsystem, you cannot use gbde with vinum volumes. Daniel Gerzo Contributed by Disk Encryption with <command>geli</command> A new cryptographic GEOM class is available as of &os; 6.0 - geli. It is currently being developed by &a.pjd;. Geli is different to gbde; it offers different features and uses a different scheme for doing cryptographic work. The most important features of &man.geli.8; are: Utilizes the &man.crypto.9; framework — when cryptographic hardware is available, geli will use it automatically. Supports multiple cryptographic algorithms (currently AES, Blowfish, and 3DES). Allows the root partition to be encrypted. The passphrase used to access the encrypted root partition will be requested during the system boot. Allows the use of two independent keys (e.g. a key and a company key). geli is fast - performs simple sector-to-sector encryption. Allows backup and restore of Master Keys. When a user has to destroy his keys, it will be possible to get access to the data again by restoring keys from the backup. Allows to attach a disk with a random, one-time key — useful for swap partitions and temporary file systems. More geli features can be found in the &man.geli.8; manual page. The next steps will describe how to enable support for geli in the &os; kernel and will explain how to create a new geli encryption provider. At the end it will be demonstrated how to create an encrypted swap partition using features provided by geli. In order to use geli, you must be running &os; 6.0-RELEASE or later. Super-user privileges will be required since modifications to the kernel are necessary. Adding <command>geli</command> Support to the Kernel Configuration File Add the following lines to the kernel configuration file: options GEOM_ELI device crypto Rebuild the kernel as described in . Alternatively, the geli module can be loaded at boot time. Add the following line to the /boot/loader.conf: geom_eli_load="YES" &man.geli.8; should now be supported by the kernel. Generating the Master Key The following example will describe how to generate a key file, which will be used as part of the Master Key for the encrypted provider mounted under /private. The key file will provide some random data used to encrypt the Master Key. The Master Key will be protected by a passphrase as well. Provider's sector size will be 4kB big. Furthermore, the discussion will describe how to attach the geli provider, create a file system on it, how to mount it, how to work with it, and finally how to detach it. It is recommended to use a bigger sector size (like 4kB) for better performance. The Master Key will be protected with a passphrase and the data source for key file will be /dev/random. The sector size of /dev/da2.eli, which we call provider, will be 4kB. &prompt.root; dd if=/dev/random of=/root/da2.key bs=64 count=1 &prompt.root; geli init -s 4096 -K /root/da2.key /dev/da2 Enter new passphrase: Reenter new passphrase: It is not mandatory that both a passphrase and a key file are used; either method of securing the Master Key can be used in isolation. If key file is given as -, standard input will be used. This example shows how more than one key file can be used. &prompt.root; cat keyfile1 keyfile2 keyfile3 | geli init -K - /dev/da2 Attaching the Provider with the generated Key &prompt.root; geli attach -k /root/da2.key /dev/da2 Enter passphrase: The new plaintext device will be named /dev/da2.eli. &prompt.root; ls /dev/da2* /dev/da2 /dev/da2.eli Creating the new File System &prompt.root; dd if=/dev/random of=/dev/da2.eli bs=1m &prompt.root; newfs /dev/da2.eli &prompt.root; mount /dev/da2.eli /private The encrypted file system should be visible to &man.df.1; and be available for use now. &prompt.root; df -H Filesystem Size Used Avail Capacity Mounted on /dev/ad0s1a 248M 89M 139M 38% / /devfs 1.0K 1.0K 0B 100% /dev /dev/ad0s1f 7.7G 2.3G 4.9G 32% /usr /dev/ad0s1d 989M 1.5M 909M 0% /tmp /dev/ad0s1e 3.9G 1.3G 2.3G 35% /var /dev/da2.eli 150G 4.1K 138G 0% /private Unmounting and Detaching the Provider Once the work on the encrypted partition is done, and the /private partition is no longer needed, it is prudent to consider unmounting and detaching the geli encrypted partition from the kernel. &prompt.root; umount /private &prompt.root; geli detach da2.eli More information about the use of &man.geli.8; can be found in the manual page. Using the <filename>geli</filename> <filename>rc.d</filename> Script geli comes with a rc.d script which can be used to simplify the usage of geli. An example of configuring geli through &man.rc.conf.5; follows: geli_devices="da2" geli_da2_flags="-p -k /root/da2.key" This will configure /dev/da2 as a geli provider of which the Master Key file is located in /root/da2.key, and geli will not use a passphrase when attaching the provider (note that this can only be used if -P was given during the geli init phase). The system will detach the geli provider from the kernel before the system shuts down. More information about configuring rc.d is provided in the rc.d section of the Handbook. Christian Brüffer Written by Encrypting Swap Space swap encrypting Swap encryption in &os; is easy to configure and has been available since &os; 5.3-RELEASE. Depending on which version of &os; is being used, different options are available and configuration can vary slightly. From &os; 6.0-RELEASE onwards, the &man.gbde.8; or &man.geli.8; encryption systems can be used for swap encryption. With earlier versions, only &man.gbde.8; is available. Both systems use the encswap rc.d script. The previous section, Encrypting Disk Partitions, includes a short discussion on the different encryption systems. Why should Swap be Encrypted? Like the encryption of disk partitions, encryption of swap space is done to protect sensitive information. Imagine an application that e.g. deals with passwords. As long as these passwords stay in physical memory, all is well. However, if the operating system starts swapping out memory pages to free space for other applications, the passwords may be written to the disk platters unencrypted and easy to retrieve for an adversary. Encrypting swap space can be a solution for this scenario. Preparation For the remainder of this section, ad0s1b will be the swap partition. Up to this point the swap has been unencrypted. It is possible that there are already passwords or other sensitive data on the disk platters in cleartext. To rectify this, the data on the swap partition should be overwritten with random garbage: &prompt.root; dd if=/dev/random of=/dev/ad0s1b bs=1m Swap Encryption with &man.gbde.8; If &os; 6.0-RELEASE or newer is being used, the .bde suffix should be added to the device in the respective /etc/fstab swap line: # Device Mountpoint FStype Options Dump Pass# /dev/ad0s1b.bde none swap sw 0 0 For systems prior to &os; 6.0-RELEASE, the following line in /etc/rc.conf is also needed: gbde_swap_enable="YES" Swap Encryption with &man.geli.8; Alternatively, the procedure for using &man.geli.8; for swap encryption is similar to that of using &man.gbde.8;. The .eli suffix should be added to the device in the respective /etc/fstab swap line: # Device Mountpoint FStype Options Dump Pass# /dev/ad0s1b.eli none swap sw 0 0 &man.geli.8; uses the AES algorithm with a key length of 256 bit by default. Optionally, these defaults can be altered using the geli_swap_flags option in /etc/rc.conf. The following line tells the encswap rc.d script to create &man.geli.8; swap partitions using the Blowfish algorithm with a key length of 128 bit, a sectorsize of 4 kilobytes and the detach on last close option set: geli_swap_flags="-a blowfish -l 128 -s 4096 -d" Please refer to the description of the onetime command in the &man.geli.8; manual page for a list of possible options. Verifying that it Works Once the system has been rebooted, proper operation of the encrypted swap can be verified using the swapinfo command. If &man.gbde.8; is being used: &prompt.user; swapinfo Device 1K-blocks Used Avail Capacity /dev/ad0s1b.bde 542720 0 542720 0% If &man.geli.8; is being used: &prompt.user; swapinfo Device 1K-blocks Used Avail Capacity /dev/ad0s1b.eli 542720 0 542720 0%