Index: cddl/contrib/opensolaris/cmd/zpool/zpool-features.7 =================================================================== --- cddl/contrib/opensolaris/cmd/zpool/zpool-features.7 +++ cddl/contrib/opensolaris/cmd/zpool/zpool-features.7 @@ -1,629 +1,606 @@ '\" te -.\" Copyright (c) 2012, Martin Matuska . -.\" All Rights Reserved. -.\" -.\" The contents of this file are subject to the terms of the -.\" Common Development and Distribution License (the "License"). -.\" You may not use this file except in compliance with the License. -.\" -.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE -.\" or http://www.opensolaris.org/os/licensing. -.\" See the License for the specific language governing permissions -.\" and limitations under the License. -.\" -.\" When distributing Covered Code, include this CDDL HEADER in each -.\" file and include the License file at usr/src/OPENSOLARIS.LICENSE. -.\" If applicable, add the following below this CDDL HEADER, with the -.\" fields enclosed by brackets "[]" replaced with your own identifying -.\" information: Portions Copyright [yyyy] [name of copyright owner] -.\" -.\" Copyright (c) 2012, 2017 by Delphix. All rights reserved. +.\" Copyright (c) 2012, Martin Matuska . All Rights Reserved. +.\" Copyright (c) 2013, 2017 by Delphix. All rights reserved. .\" Copyright (c) 2013 by Saso Kiselkov. All rights reserved. -.\" Copyright (c) 2013, Joyent, Inc. All rights reserved. +.\" Copyright (c) 2014, Joyent, Inc. All rights reserved. +.\" Copyright (c) 2014 Integros [integros.com] +.\" The contents of this file are subject to the terms of the Common Development +.\" and Distribution License (the "License"). You may not use this file except +.\" in compliance with the License. You can obtain a copy of the license at +.\" usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing. .\" +.\" See the License for the specific language governing permissions and +.\" limitations under the License. When distributing Covered Code, include this +.\" CDDL HEADER in each file and include the License file at +.\" usr/src/OPENSOLARIS.LICENSE. If applicable, add the following below this +.\" CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your +.\" own identifying information: +.\" Portions Copyright [yyyy] [name of copyright owner] +.\" .\" $FreeBSD$ .\" -.Dd June 7, 2017 -.Dt ZPOOL-FEATURES 7 -.Os -.Sh NAME -.Nm zpool-features -.Nd ZFS pool feature descriptions -.Sh DESCRIPTION +.TH ZPOOL-FEATURES 7 "Dec 9, 2018" +.SH NAME +zpool\-features \- ZFS pool feature descriptions +.SH DESCRIPTION +.LP ZFS pool on\-disk format versions are specified via "features" which replace the old on\-disk format numbers (the last supported on\-disk format number is -28). -To enable a feature on a pool use the -.Cm upgrade -subcommand of the -.Xr zpool 8 -command, or set the -.Sy feature@feature_name -property to -.Ar enabled . -.Pp +28). To enable a feature on a pool use the \fBupgrade\fR subcommand of the +\fBzpool\fR(8) command, or set the \fBfeature@\fR\fIfeature_name\fR property +to \fBenabled\fR. +.sp +.LP The pool format does not affect file system version compatibility or the ability to send file systems between pools. -.Pp +.sp +.LP Since most features can be enabled independently of each other the on\-disk format of the pool is specified by the set of all features marked as -.Sy active -on the pool. -If the pool was created by another software version this set may -include unsupported features. -.Ss Identifying features -Every feature has a guid of the form -.Sy com.example:feature_name . -The reverse DNS name ensures that the feature's guid is unique across all ZFS -implementations. -When unsupported features are encountered on a pool they will -be identified by their guids. -Refer to the documentation for the ZFS implementation that created the pool -for information about those features. -.Pp -Each supported feature also has a short name. -By convention a feature's short name is the portion of its guid which follows -the ':' (e.g. -.Sy com.example:feature_name -would have the short name -.Sy feature_name ), +\fBactive\fR on the pool. If the pool was created by another software version +this set may include unsupported features. +.SS "Identifying features" +.LP +Every feature has a guid of the form \fIcom.example:feature_name\fR. The reverse +DNS name ensures that the feature's guid is unique across all ZFS +implementations. When unsupported features are encountered on a pool they will +be identified by their guids. Refer to the documentation for the ZFS +implementation that created the pool for information about those features. +.sp +.LP +Each supported feature also has a short name. By convention a feature's short +name is the portion of its guid which follows the ':' (e.g. +\fIcom.example:feature_name\fR would have the short name \fIfeature_name\fR), however a feature's short name may differ across ZFS implementations if following the convention would result in name conflicts. -.Ss Feature states +.SS "Feature states" +.LP Features can be in one of three states: -.Bl -tag -width "XXXXXXXX" -.It Sy active -This feature's on\-disk format changes are in effect on the pool. -Support for this feature is required to import the pool in read\-write mode. -If this feature is not read-only compatible, support is also required to -import the pool in read\-only mode (see "Read\-only compatibility"). -.It Sy enabled +.sp +.ne 2 +.na +\fB\fBactive\fR\fR +.ad +.RS 12n +This feature's on\-disk format changes are in effect on the pool. Support for +this feature is required to import the pool in read\-write mode. If this +feature is not read-only compatible, support is also required to import the pool +in read\-only mode (see "Read\-only compatibility"). +.RE + +.sp +.ne 2 +.na +\fB\fBenabled\fR\fR +.ad +.RS 12n An administrator has marked this feature as enabled on the pool, but the -feature's on\-disk format changes have not been made yet. -The pool can still be imported by software that does not support this feature, -but changes may be made to the on\-disk format at any time which will move -the feature to the -.Sy active -state. -Some features may support returning to the -.Sy enabled -state after becoming -.Sy active . -See feature\-specific documentation for details. -.It Sy disabled +feature's on\-disk format changes have not been made yet. The pool can still be +imported by software that does not support this feature, but changes may be made +to the on\-disk format at any time which will move the feature to the +\fBactive\fR state. Some features may support returning to the \fBenabled\fR +state after becoming \fBactive\fR. See feature\-specific documentation for +details. +.RE + +.sp +.ne 2 +.na +\fBdisabled\fR +.ad +.RS 12n This feature's on\-disk format changes have not been made and will not be made -unless an administrator moves the feature to the -.Sy enabled -state. -Features cannot be disabled once they have been enabled. -.El -.Pp +unless an administrator moves the feature to the \fBenabled\fR state. Features +cannot be disabled once they have been enabled. +.RE + +.sp +.LP The state of supported features is exposed through pool properties of the form -.Sy feature@short_name . -.Ss Read\-only compatibility +\fIfeature@short_name\fR. +.SS "Read\-only compatibility" +.LP Some features may make on\-disk format changes that do not interfere with other -software's ability to read from the pool. -These features are referred to as "read\-only compatible". -If all unsupported features on a pool are read\-only compatible, the pool can -be imported in read\-only mode by setting the -.Sy readonly -property during import (see -.Xr zpool 8 -for details on importing pools). -.Ss Unsupported features +software's ability to read from the pool. These features are referred to as +"read\-only compatible". If all unsupported features on a pool are read\-only +compatible, the pool can be imported in read\-only mode by setting the +\fBreadonly\fR property during import (see \fBzpool\fR(8) for details on +importing pools). +.SS "Unsupported features" +.LP For each unsupported feature enabled on an imported pool a pool property -named -.Sy unsupported@feature_guid -will indicate why the import was allowed despite the unsupported feature. -Possible values for this property are: -.Bl -tag -width "XXXXXXXX" -.It Sy inactive -The feature is in the -.Sy enabled -state and therefore the pool's on\-disk format is still compatible with -software that does not support this feature. -.It Sy readonly +named \fIunsupported@feature_guid\fR will indicate why the import was allowed +despite the unsupported feature. Possible values for this property are: + +.sp +.ne 2 +.na +\fB\fBinactive\fR\fR +.ad +.RS 12n +The feature is in the \fBenabled\fR state and therefore the pool's on\-disk +format is still compatible with software that does not support this feature. +.RE + +.sp +.ne 2 +.na +\fB\fBreadonly\fR\fR +.ad +.RS 12n The feature is read\-only compatible and the pool has been imported in read\-only mode. -.El -.Ss Feature dependencies +.RE + +.SS "Feature dependencies" +.LP Some features depend on other features being enabled in order to function -properly. -Enabling a feature will automatically enable any features it depends on. -.Sh FEATURES +properly. Enabling a feature will automatically enable any features it +depends on. +.SH FEATURES +.LP The following features are supported on this system: -.Bl -tag -width "XXXXXXXX" -.It Sy async_destroy -.Bl -column "READ\-ONLY COMPATIBLE" "com.delphix:async_destroy" -.It GUID Ta com.delphix:async_destroy -.It READ\-ONLY COMPATIBLE Ta yes -.It DEPENDENCIES Ta none -.El -.Pp +.sp +.ne 2 +.na +\fB\fBasync_destroy\fR\fR +.ad +.RS 4n +.TS +l l . +GUID com.delphix:async_destroy +READ\-ONLY COMPATIBLE yes +DEPENDENCIES none +.TE + Destroying a file system requires traversing all of its data in order to -return its used space to the pool. -Without -.Sy async_destroy -the file system is not fully removed until all space has been reclaimed. -If the destroy operation is interrupted by a reboot or power outage the next -attempt to open the pool will need to complete the destroy operation -synchronously. -.Pp -When -.Sy async_destroy -is enabled the file system's data will be reclaimed by a background process, -allowing the destroy operation to complete without traversing the entire file -system. -The background process is able to resume interrupted destroys after the pool -has been opened, eliminating the need to finish interrupted destroys as part -of the open operation. -The amount of space remaining to be reclaimed by the background process is -available through the -.Sy freeing -property. -.Pp -This feature is only -.Sy active -while -.Sy freeing -is non\-zero. -.It Sy empty_bpobj -.Bl -column "READ\-ONLY COMPATIBLE" "com.delphix:empty_bpobj" -.It GUID Ta com.delphix:empty_bpobj -.It READ\-ONLY COMPATIBLE Ta yes -.It DEPENDENCIES Ta none -.El -.Pp -This feature increases the performance of creating and using a large number -of snapshots of a single filesystem or volume, and also reduces the disk -space required. -.Pp -When there are many snapshots, each snapshot uses many Block Pointer Objects -.Pq bpobj's -to track blocks associated with that snapshot. -However, in common use cases, most of these bpobj's are empty. -This feature allows us to create each bpobj on-demand, thus eliminating the +return its used space to the pool. Without \fBasync_destroy\fR the file system +is not fully removed until all space has been reclaimed. If the destroy +operation is interrupted by a reboot or power outage the next attempt to open +the pool will need to complete the destroy operation synchronously. + +When \fBasync_destroy\fR is enabled the file system's data will be reclaimed +by a background process, allowing the destroy operation to complete without +traversing the entire file system. The background process is able to resume +interrupted destroys after the pool has been opened, eliminating the need +to finish interrupted destroys as part of the open operation. The amount +of space remaining to be reclaimed by the background process is available +through the \fBfreeing\fR property. + +This feature is only \fBactive\fR while \fBfreeing\fR is non\-zero. +.RE + +.sp +.ne 2 +.na +\fB\fBempty_bpobj\fR\fR +.ad +.RS 4n +.TS +l l . +GUID com.delphix:empty_bpobj +READ\-ONLY COMPATIBLE yes +DEPENDENCIES none +.TE + +This feature increases the performance of creating and using a large +number of snapshots of a single filesystem or volume, and also reduces +the disk space required. + +When there are many snapshots, each snapshot uses many Block Pointer +Objects (bpobj's) to track blocks associated with that snapshot. +However, in common use cases, most of these bpobj's are empty. This +feature allows us to create each bpobj on-demand, thus eliminating the empty bpobjs. -.Pp -This feature is -.Sy active -while there are any filesystems, volumes, or snapshots which were created -after enabling this feature. -.It Sy filesystem_limits -.Bl -column "READ\-ONLY COMPATIBLE" "com.joyent:filesystem_limits" -.It GUID Ta com.joyent:filesystem_limits -.It READ\-ONLY COMPATIBLE Ta yes -.It DEPENDENCIES Ta extensible_dataset -.El -.Pp -This feature enables filesystem and snapshot limits. -These limits can be used + +This feature is \fBactive\fR while there are any filesystems, volumes, +or snapshots which were created after enabling this feature. +.RE + +.sp +.ne 2 +.na +\fB\fBfilesystem_limits\fR\fR +.ad +.RS 4n +.TS +l l . +GUID com.joyent:filesystem_limits +READ\-ONLY COMPATIBLE yes +DEPENDENCIES extensible_dataset +.TE + +This feature enables filesystem and snapshot limits. These limits can be used to control how many filesystems and/or snapshots can be created at the point in the tree on which the limits are set. -.Pp -This feature is -.Sy active -once either of the limit properties has been -set on a dataset. -Once activated the feature is never deactivated. -.It Sy lz4_compress -.Bl -column "READ\-ONLY COMPATIBLE" "org.illumos:lz4_compress" -.It GUID Ta org.illumos:lz4_compress -.It READ\-ONLY COMPATIBLE Ta no -.It DEPENDENCIES Ta none -.El -.Pp -.Sy lz4 -is a high-performance real-time compression algorithm that + +This feature is \fBactive\fR once either of the limit properties has been +set on a dataset. Once activated the feature is never deactivated. +.RE + +.sp +.ne 2 +.na +\fB\fBlz4_compress\fR\fR +.ad +.RS 4n +.TS +l l . +GUID org.illumos:lz4_compress +READ\-ONLY COMPATIBLE no +DEPENDENCIES none +.TE + +\fBlz4\fR is a high-performance real-time compression algorithm that features significantly faster compression and decompression as well as a -higher compression ratio than the older -.Sy lzjb -compression. -Typically, -.Sy lz4 -compression is approximately 50% faster on +higher compression ratio than the older \fBlzjb\fR compression. +Typically, \fBlz4\fR compression is approximately 50% faster on compressible data and 200% faster on incompressible data than -.Sy lzjb . -It is also approximately 80% faster on decompression, while +\fBlzjb\fR. It is also approximately 80% faster on decompression, while giving approximately 10% better compression ratio. -.Pp -When the -.Sy lz4_compress -feature is set to -.Sy enabled , -the -administrator can turn on -.Sy lz4 -compression on any dataset on the -pool using the -.Xr zfs 8 -command. -Also, all newly written metadata -will be compressed with -.Sy lz4 -algorithm. -Since this feature is not read-only compatible, this -operation will render the pool unimportable on systems without support -for the -.Sy lz4_compress -feature. -Booting off of -.Sy lz4 --compressed root pools is supported. -.Pp -This feature becomes -.Sy active -as soon as it is enabled and will -never return to being -.Sy enabled . -.It Sy multi_vdev_crash_dump -.Bl -column "READ\-ONLY COMPATIBLE" "com.joyent:multi_vdev_crash_dump" -.It GUID Ta com.joyent:multi_vdev_crash_dump -.It READ\-ONLY COMPATIBLE Ta no -.It DEPENDENCIES Ta none -.El -.Pp + +When the \fBlz4_compress\fR feature is set to \fBenabled\fR, the +administrator can turn on \fBlz4\fR compression on any dataset on the +pool using the \fBzfs\fR(8) command. Also, all newly written metadata +will be compressed with \fBlz4\fR algorithm. Since this feature is not +read-only compatible, this operation will render the pool unimportable +on systems without support for the \fBlz4_compress\fR feature. Booting +off of \fBlz4\fR-compressed root pools is supported. + +This feature becomes \fBactive\fR as soon as it is enabled and will +never return to being \fBenabled\fR. +.RE + +.sp +.ne 2 +.na +\fB\fBspacemap_histogram\fR\fR +.ad +.RS 4n +.TS +l l . +GUID com.delphix:spacemap_histogram +READ\-ONLY COMPATIBLE yes +DEPENDENCIES none +.TE + +This features allows ZFS to maintain more information about how free space +is organized within the pool. If this feature is \fBenabled\fR, ZFS will +set this feature to \fBactive\fR when a new space map object is created or +an existing space map is upgraded to the new format. Once the feature is +\fBactive\fR, it will remain in that state until the pool is destroyed. +.RE + +.sp +.ne 2 +.na +\fB\fBmulti_vdev_crash_dump\fR\fR +.ad +.RS 4n +.TS +l l . +GUID com.joyent:multi_vdev_crash_dump +READ\-ONLY COMPATIBLE no +DEPENDENCIES none +.TE + This feature allows a dump device to be configured with a pool comprised -of multiple vdevs. -Those vdevs may be arranged in any mirrored or raidz +of multiple vdevs. Those vdevs may be arranged in any mirrored or raidz configuration. -.\" TODO: this is not yet supported on FreeBSD. -.\" .Pp -.\" When the -.\" .Sy multi_vdev_crash_dump -.\" feature is set to -.\" .Sy enabled , -.\" the administrator can use the -.\" .Xr dumpon 8 -.\" command to configure a -.\" dump device on a pool comprised of multiple vdevs. -.It Sy spacemap_histogram -.Bl -column "READ\-ONLY COMPATIBLE" "com.delphix:spacemap_histogram" -.It GUID Ta com.delphix:spacemap_histogram -.It READ\-ONLY COMPATIBLE Ta yes -.It DEPENDENCIES Ta none -.El -.Pp -This features allows ZFS to maintain more information about how free space -is organized within the pool. -If this feature is -.Sy enabled , -ZFS will -set this feature to -.Sy active -when a new space map object is created or -an existing space map is upgraded to the new format. -Once the feature is -.Sy active , -it will remain in that state until the pool is destroyed. -.It Sy extensible_dataset -.Bl -column "READ\-ONLY COMPATIBLE" "com.delphix:extensible_dataset" -.It GUID Ta com.delphix:extensible_dataset -.It READ\-ONLY COMPATIBLE Ta no -.It DEPENDENCIES Ta none -.El -.Pp + +Under FreeBSD this feature is registered for compatibility but not used. +New pools created under FreeBSD will have the feature \fBenabled\fR but +will never transition to \fB\fBactive\fR. Existing pools +where this feature is \fB\fBactive\fR can be imported. +.RE + +.sp +.ne 2 +.na +\fB\fBextensible_dataset\fR\fR +.ad +.RS 4n +.TS +l l . +GUID com.delphix:extensible_dataset +READ\-ONLY COMPATIBLE no +DEPENDENCIES none +.TE + This feature allows more flexible use of internal ZFS data structures, and exists for other features to depend on. -.Pp -This feature will be -.Sy active -when the first dependent feature uses it, -and will be returned to the -.Sy enabled -state when all datasets that use + +This feature will be \fBactive\fR when the first dependent feature uses it, +and will be returned to the \fBenabled\fR state when all datasets that use this feature are destroyed. -.It Sy bookmarks -.Bl -column "READ\-ONLY COMPATIBLE" "com.delphix:bookmarks" -.It GUID Ta com.delphix:bookmarks -.It READ\-ONLY COMPATIBLE Ta yes -.It DEPENDENCIES Ta extensible_dataset -.El -.Pp -This feature enables use of the -.Nm zfs -.Cm bookmark -subcommand. -.Pp -This feature is -.Sy active -while any bookmarks exist in the pool. + +.RE + +.sp +.ne 2 +.na +\fB\fBbookmarks\fR\fR +.ad +.RS 4n +.TS +l l . +GUID com.delphix:bookmarks +READ\-ONLY COMPATIBLE yes +DEPENDENCIES extensible_dataset +.TE + +This feature enables use of the \fBzfs bookmark\fR subcommand. + +This feature is \fBactive\fR while any bookmarks exist in the pool. All bookmarks in the pool can be listed by running -.Nm zfs -.Cm list -.Fl t No bookmark Fl r Ar poolname . -.It Sy enabled_txg -.Bl -column "READ\-ONLY COMPATIBLE" "com.delphix:enabled_txg" -.It GUID Ta com.delphix:enabled_txg -.It READ\-ONLY COMPATIBLE Ta yes -.It DEPENDENCIES Ta none -.El -.Pp +\fBzfs list -t bookmark -r \fIpoolname\fR\fR. + +.RE + +.sp +.ne 2 +.na +\fB\fBenabled_txg\fR\fR +.ad +.RS 4n +.TS +l l . +GUID com.delphix:enabled_txg +READ\-ONLY COMPATIBLE yes +DEPENDENCIES none +.TE + Once this feature is enabled ZFS records the transaction group number -in which new features are enabled. -This has no user-visible impact, +in which new features are enabled. This has no user-visible impact, but other features may depend on this feature. -.Pp -This feature becomes -.Sy active -as soon as it is enabled and will -never return to being -.Sy enabled . -.It Sy hole_birth -.Bl -column "READ\-ONLY COMPATIBLE" "com.delphix:hole_birth" -.It GUID Ta com.delphix:hole_birth -.It READ\-ONLY COMPATIBLE Ta no -.It DEPENDENCIES Ta enabled_txg -.El -.Pp -This feature improves performance of incremental sends -.Pq Dq zfs send -i -and receives for objects with many holes. -The most common case of + +This feature becomes \fBactive\fR as soon as it is enabled and will +never return to being \fBenabled\fR. + +.RE + +.sp +.ne 2 +.na +\fB\fBhole_birth\fR\fR +.ad +.RS 4n +.TS +l l . +GUID com.delphix:hole_birth +READ\-ONLY COMPATIBLE no +DEPENDENCIES enabled_txg +.TE + +This feature improves performance of incremental sends ("zfs send -i") +and receives for objects with many holes. The most common case of hole-filled objects is zvols. -.Pp -An incremental send stream from snapshot -.Sy A -to snapshot -.Sy B -contains information about every block that changed between -.Sy A -and -.Sy B . -Blocks which did not change between those snapshots can be + +An incremental send stream from snapshot \fBA\fR to snapshot \fBB\fR +contains information about every block that changed between \fBA\fR and +\fBB\fR. Blocks which did not change between those snapshots can be identified and omitted from the stream using a piece of metadata called -the 'block birth time', but birth times are not recorded for holes -.Pq blocks filled only with zeroes . -Since holes created after -.Sy A -cannot be -distinguished from holes created before -.Sy A , -information about every +the 'block birth time', but birth times are not recorded for holes (blocks +filled only with zeroes). Since holes created after \fBA\fR cannot be +distinguished from holes created before \fBA\fR, information about every hole in the entire filesystem or zvol is included in the send stream. -.Pp -For workloads where holes are rare this is not a problem. -However, when -incrementally replicating filesystems or zvols with many holes -.Pq for example a zvol formatted with another filesystem -a lot of time will + +For workloads where holes are rare this is not a problem. However, when +incrementally replicating filesystems or zvols with many holes (for +example a zvol formatted with another filesystem) a lot of time will be spent sending and receiving unnecessary information about holes that already exist on the receiving side. -.Pp -Once the -.Sy hole_birth -feature has been enabled the block birth times -of all new holes will be recorded. -Incremental sends between snapshots + +Once the \fBhole_birth\fR feature has been enabled the block birth times +of all new holes will be recorded. Incremental sends between snapshots created after this feature is enabled will use this new metadata to avoid sending information about holes that already exist on the receiving side. -.Pp -This feature becomes -.Sy active -as soon as it is enabled and will -never return to being -.Sy enabled . -.It Sy embedded_data -.Bl -column "READ\-ONLY COMPATIBLE" "com.delphix:embedded_data" -.It GUID Ta com.delphix:embedded_data -.It READ\-ONLY COMPATIBLE Ta no -.It DEPENDENCIES Ta none -.El -.Pp + +This feature becomes \fBactive\fR as soon as it is enabled and will +never return to being \fBenabled\fR. + +.RE + +.sp +.ne 2 +.na +\fB\fBembedded_data\fR\fR +.ad +.RS 4n +.TS +l l . +GUID com.delphix:embedded_data +READ\-ONLY COMPATIBLE no +DEPENDENCIES none +.TE + This feature improves the performance and compression ratio of -highly-compressible blocks. -Blocks whose contents can compress to 112 bytes +highly-compressible blocks. Blocks whose contents can compress to 112 bytes or smaller can take advantage of this feature. -.Pp + When this feature is enabled, the contents of highly-compressible blocks are -stored in the block "pointer" itself -.Po a misnomer in this case, as it contains -the compressed data, rather than a pointer to its location on disk -.Pc . -Thus -the space of the block -.Pq one sector, typically 512 bytes or 4KB -is saved, +stored in the block "pointer" itself (a misnomer in this case, as it contains +the compresseed data, rather than a pointer to its location on disk). Thus +the space of the block (one sector, typically 512 bytes or 4KB) is saved, and no additional i/o is needed to read and write the data block. -.Pp -This feature becomes -.Sy active -as soon as it is enabled and will -never return to being -.Sy enabled . -.It Sy zpool_checkpoint -.Bl -column "READ\-ONLY COMPATIBLE" "com.delphix:zpool_checkpoint" -.It GUID Ta com.delphix:zpool_checkpoint -.It READ\-ONLY COMPATIBLE Ta yes -.It DEPENDENCIES Ta none -.El -.Pp -This feature enables the "zpool checkpoint" subcommand that can -checkpoint the state of the pool at the time it was issued and later -rewind back to it or discard it. -.Pp -This feature becomes -.Sy active -when the "zpool checkpoint" command is used to checkpoint the pool. -The feature will only return back to being -.Sy enabled -when the pool is rewound or the checkpoint has been discarded. -.It Sy device_removal -.Bl -column "READ\-ONLY COMPATIBLE" "com.delphix:device_removal" -.It GUID Ta com.delphix:device_removal -.It READ\-ONLY COMPATIBLE Ta no -.It DEPENDENCIES Ta none -.El -.Pp + +This feature becomes \fBactive\fR as soon as it is enabled and will +never return to being \fBenabled\fR. + +.RE +.sp +.ne 2 +.na +\fB\fBdevice_removal\fR\fR +.ad +.RS 4n +.TS +l l . +GUID com.delphix:device_removal +READ\-ONLY COMPATIBLE no +DEPENDENCIES none +.TE + This feature enables the "zpool remove" subcommand to remove top-level vdevs, evacuating them to reduce the total size of the pool. -.Pp -This feature becomes -.Sy active -when the "zpool remove" command is used -on a top-level vdev, and will never return to being -.Sy enabled . -.It Sy obsolete_counts -.Bl -column "READ\-ONLY COMPATIBLE" "com.delphix:obsolete_counts" -.It GUID Ta com.delphix:obsolete_counts -.It READ\-ONLY COMPATIBLE Ta yes -.It DEPENDENCIES Ta device_removal -.El -.Pp + +This feature becomes \fBactive\fR when the "zpool remove" command is used +on a top-level vdev, and will never return to being \fBenabled\fR. + +.RE +.sp +.ne 2 +.na +\fB\fBobsolete_counts\fR\fR +.ad +.RS 4n +.TS +l l . +GUID com.delphix:obsolete_counts +READ\-ONLY COMPATIBLE yes +DEPENDENCIES device_removal +.TE + This feature is an enhancement of device_removal, which will over time reduce the memory used to track removed devices. When indirect blocks are freed or remapped, we note that their part of the indirect mapping -is "obsolete", i.e. no longer needed. See also the "zfs remap" -subcommand in -.Xr zfs 8 . +is "obsolete", i.e. no longer needed. See also the \fBzfs remap\fR +subcommand in \fBzfs\fR(8). -This feature becomes -.Sy active -when the "zpool remove" command is -used on a top-level vdev, and will never return to being -.Sy enabled . -.It Sy spacemap_v2 -.Bl -column "READ\-ONLY COMPATIBLE" "com.delphix:spacemap_v2" -.It GUID Ta com.delphix:spacemap_v2 -.It READ\-ONLY COMPATIBLE Ta yes -.It DEPENDENCIES Ta none -.El -.Pp +This feature becomes \fBactive\fR when the "zpool remove" command is +used on a top-level vdev, and will never return to being \fBenabled\fR. + +.RE +.sp +.ne 2 +.na +\fB\fBzpool_checkpoint\fR\fR +.ad +.RS 4n +.TS +l l . +GUID com.delphix:zpool_checkpoint +READ\-ONLY COMPATIBLE yes +DEPENDENCIES none +.TE + +This feature enables the "zpool checkpoint" subcommand that can +checkpoint the state of the pool at the time it was issued and later +rewind back to it or discard it. + +This feature becomes \fBactive\fR when the "zpool checkpoint" command +is used to checkpoint the pool. +The feature will only return back to being \fBenabled\fR when the pool +is rewound or the checkpoint has been discarded. + +.RE +.sp +.ne 2 +.na +\fB\fBspacemap_v2\fR\fR +.ad +.RS 4n +.TS +l l . +GUID com.delphix:spacemap_v2 +READ\-ONLY COMPATIBLE yes +DEPENDENCIES none +.TE + This feature enables the use of the new space map encoding which consists of two words (instead of one) whenever it is advantageous. The new encoding allows space maps to represent large regions of space more efficiently on-disk while also increasing their maximum addressable offset. -.Pp -This feature becomes -.Sy active -as soon as it is enabled and will -never return to being -.Sy enabled . -.It Sy large_blocks -.Bl -column "READ\-ONLY COMPATIBLE" "org.open-zfs:large_block" -.It GUID Ta org.open-zfs:large_block -.It READ\-ONLY COMPATIBLE Ta no -.It DEPENDENCIES Ta extensible_dataset -.El -.Pp -The -.Sy large_block -feature allows the record size on a dataset to be + +This feature becomes \fBactive\fR once it is \fBenabled\fR, and never +returns back to being \fBenabled\fR. + +.RE +.sp +.ne 2 +.na +\fB\fBlarge_blocks\fR\fR +.ad +.RS 4n +.TS +l l . +GUID org.open-zfs:large_block +READ\-ONLY COMPATIBLE no +DEPENDENCIES extensible_dataset +.TE + +The \fBlarge_block\fR feature allows the record size on a dataset to be set larger than 128KB. -.Pp -This feature becomes -.Sy active -once a -.Sy recordsize -property has been set larger than 128KB, and will return to being -.Sy enabled -once all filesystems that have ever had their recordsize larger than 128KB -are destroyed. -.Pp -Please note that booting from datasets that have recordsize greater than -128KB is -.Em NOT -supported by the -.Fx -boot loader. -.It Sy sha512 -.Bl -column "READ\-ONLY COMPATIBLE" "org.illumos:sha512" -.It GUID Ta org.illumos:sha512 -.It READ\-ONLY COMPATIBLE Ta no -.It DEPENDENCIES Ta none -.El -.Pp -The -.Sy sha512 -feature enables the use of the SHA-512/256 truncated hash algorithm -.Pq FIPS 180-4 -for checksum and dedup. -The native 64-bit arithmetic of SHA-512 provides an approximate 50% -performance boost over SHA-256 on 64-bit hardware and is thus a good -minimum-change replacement candidate for systems where hash performance is -important, but these systems cannot for whatever reason utilize the faster -.Sy skein -algorithms. -.Pp -When the -.Sy sha512 -feature is set to -.Sy enabled , -the administrator can turn on the -.Sy sha512 -checksum on any dataset using the -.Dl # zfs set checksum=sha512 Ar dataset -command. -This feature becomes -.Sy active -once a -.Sy checksum -property has been set to -.Sy sha512 , -and will return to being -.Sy enabled -once all filesystems that have ever had their checksum set to -.Sy sha512 -are destroyed. -.It Sy skein -.Bl -column "READ\-ONLY COMPATIBLE" "org.illumos:skein" -.It GUID Ta org.illumos:skein -.It READ\-ONLY COMPATIBLE Ta no -.It DEPENDENCIES Ta none -.El -.Pp -The -.Sy skein -feature enables the use of the Skein hash algorithm for checksum and dedup. -Skein is a high-performance secure hash algorithm that was a finalist in the -NIST SHA-3 competition. -It provides a very high security margin and high performance on 64-bit hardware -.Pq 80% faster than SHA-256 . -This implementation also utilizes the new salted checksumming functionality in -ZFS, which means that the checksum is pre-seeded with a secret 256-bit random -key -.Pq stored on the pool -before being fed the data block to be checksummed. -Thus the produced checksums are unique to a given pool, preventing hash -collision attacks on systems with dedup. -.Pp -When the -.Sy skein -feature is set to -.Sy enabled , -the administrator can turn on the -.Sy skein -checksum on any dataset using the -.Dl # zfs set checksum=skein Ar dataset -command. -This feature becomes -.Sy active -once a -.Sy checksum -property has been set to -.Sy skein , -and will return to being -.Sy enabled -once all filesystems that have ever had their checksum set to -.Sy skein -are destroyed. -.El -.Sh SEE ALSO -.Xr zpool 8 -.Sh AUTHORS -This manual page is a -.Xr mdoc 7 -reimplementation of the -.Tn illumos -manual page -.Em zpool-features(5) , -modified and customized for -.Fx -and licensed under the Common Development and Distribution License -.Pq Tn CDDL . -.Pp -The -.Xr mdoc 7 -implementation of this manual page was initially written by -.An Martin Matuska Aq mm@FreeBSD.org . + +This feature becomes \fBactive\fR once a \fBrecordsize\fR property has been +set larger than 128KB, and will return to being \fBenabled\fR once all +filesystems that have ever had their recordsize larger than 128KB are destroyed. +.RE + +.sp +.ne 2 +.na +\fB\fBsha512\fR\fR +.ad +.RS 4n +.TS +l l . +GUID org.illumos:sha512 +READ\-ONLY COMPATIBLE no +DEPENDENCIES extensible_dataset +.TE + +This feature enables the use of the SHA-512/256 truncated hash algorithm +(FIPS 180-4) for checksum and dedup. The native 64-bit arithmetic of +SHA-512 provides an approximate 50% performance boost over SHA-256 on +64-bit hardware and is thus a good minimum-change replacement candidate +for systems where hash performance is important, but these systems +cannot for whatever reason utilize the faster \fBskein\fR and +\fBedonr\fR algorithms. + +When the \fBsha512\fR feature is set to \fBenabled\fR, the administrator +can turn on the \fBsha512\fR checksum on any dataset using the +\fBzfs set checksum=sha512\fR command. This feature becomes +\fBactive\fR once a \fBchecksum\fR property has been set to \fBsha512\fR, +and will return to being \fBenabled\fR once all filesystems that have +ever had their checksum set to \fBsha512\fR are destroyed. + +Booting off of pools utilizing SHA-512/256 is supported. + +.RE + +.sp +.ne 2 +.na +\fB\fBskein\fR\fR +.ad +.RS 4n +.TS +l l . +GUID org.illumos:skein +READ\-ONLY COMPATIBLE no +DEPENDENCIES extensible_dataset +.TE + +This feature enables the use of the Skein hash algorithm for checksum +and dedup. Skein is a high-performance secure hash algorithm that was a +finalist in the NIST SHA-3 competition. It provides a very high security +margin and high performance on 64-bit hardware (80% faster than +SHA-256). This implementation also utilizes the new salted checksumming +functionality in ZFS, which means that the checksum is pre-seeded with a +secret 256-bit random key (stored on the pool) before being fed the data +block to be checksummed. Thus the produced checksums are unique to a +given pool, preventing hash collision attacks on systems with dedup. + +When the \fBskein\fR feature is set to \fBenabled\fR, the administrator +can turn on the \fBskein\fR checksum on any dataset using the +\fBzfs set checksum=skein\fR command. This feature becomes +\fBactive\fR once a \fBchecksum\fR property has been set to \fBskein\fR, +and will return to being \fBenabled\fR once all filesystems that have +ever had their checksum set to \fBskein\fR are destroyed. + +Booting off of pools using \fBskein\fR is supported. + +.SH "SEE ALSO" +\fBzfs\fR(8), \fBzpool\fR(8)