Enable ZFSd if the installation is done on ZFS

[allanjude]

Summary

Submitted By: Sean Kelly <[e-mail]>

[grahamperrin]

I would like to see it enabled.

Parts of the manual page for zfsd(8) https://man.freebsd.org/cgi/man.cgi?query=zfsd&sektion=8&manpath=freebsd-release might benefit from a little more detail.

(Somewhere, long ago, I read an explanation for FreeBSD not yet having the daemon enabled by default. I can't recall where or when, sorry, but the explanation did make sense at the time.)

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For what it's worth: in the spoiler at https://forums.freebsd.org/posts/569190 (2022-05-28) I chose to stop the daemon before performing a series of operations with GPT fdisk. I didn't state the reason for the stop, in retrospect I guess that it was to avoid an unwanted effect of the device arrival feature of zfsd – in concert or conflict with DSBMD, maybe? (Not seeking support here; just a rough note before I lose the thought.)

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Less nebulously, I have a /usr/local/sbin/suspend.sh file that includes these three lines for a trio of removable L2ARC devices:

zpool offline august gpt/cache-august
zpool offline august gpt/cache2-august
zpool offline august gpt/cache3-august

– and I do enjoy the automated on-lining by zfsd after I wake the computer, however there's a sense of unpredictability if the devices are physically reconnected before resume/wake of the computer. Related (I'll update the discussion):

• L2ARC vdev sometimes perfectly hot before sleep (suspend) of FreeBSD, suddenly cold (after wake) · openzfs/zfs · Discussion #13478