NAME
zfsd
—
ZFS fault management daemon
SYNOPSIS
zfsd |
[-d ] |
DESCRIPTION
zfsd
attempts to resolve ZFS faults that the kernel
can't resolve by itself. It listens to
devctl(4) events, which are how the kernel notifies userland of events
such as I/O errors and disk removals. zfsd
attempts to
resolve these faults by activating or deactivating hot spares and onlining
offline vdevs.
The following options are available:
-d
- Run in the foreground instead of daemonizing.
System administrators never interact with
zfsd
directly. Instead, they control its behavior
indirectly through zpool configuration. There are two ways to influence
zfsd
: assigning hotspares and setting pool
properties. Currently, only the
autoreplace
property has any effect. See
zpool(8) for details.
zfsd
will attempt to resolve the following
types of fault:
- device removal
- When a leaf vdev disappears,
zfsd
will activate any available hotspare. - device arrival
- When a new GEOM device appears,
zfsd
will attempt to read its ZFS label, if any. If it matches a previously removed vdev on an active pool,zfsd
will online it. Once resilvering completes, any active hotspare will detach automatically.If the new device has no ZFS label but its physical path matches the physical path of a previously removed vdev on an active pool, and that pool has the autoreplace property set, then
zfsd
will replace the missing vdev with the newly arrived device. Once resilvering completes, any active hotspare will detach automatically. - vdev degrade or fault events
- If a vdev becomes degraded or faulted,
zfsd
will activate any available hotspare. - I/O errors
- If a leaf vdev generates more than 50 I/O errors in a 60 second period,
then
zfsd
will mark that vdev as FAULTED. zfs(4) will no longer issue any I/Os to it.zfsd
will activate a hotspare if one is available. - Checksum errors
- If a leaf vdev generates more than 50 checksum errors in a 60 second
period, then
zfsd
will mark that vdev as DEGRADED. zfs(4) will still use it, but zfsd will activate a spare anyway. - Spare addition
- If the system administrator adds a hotspare to a pool that is already
degraded,
zfsd
will activate the spare. - Resilver complete
zfsd
will detach any hotspare once a permanent replacement finishes resilvering.- Physical path change
- If the physical path of an existing disk changes,
zfsd
will attempt to replace any missing disk with the same physical path, if its pool's autoreplace property is set.
zfsd
will log interesting
events and its actions to syslog with facility
daemon and
identity [zfsd].
FILES
- /var/db/zfsd/cases
- When
zfsd
exits, it serializes any unresolved casefiles here, then reads them back in when next it starts up.
SEE ALSO
HISTORY
zfsd
first appeared in
FreeBSD 11.0.
AUTHORS
zfsd
was originally written by
Justin Gibbs
<gibbs@FreeBSD.org>
and
Alan Somers
<asomers@FreeBSD.org>
TODO
In the future, zfsd
should be able to
resume a pool that became suspended due to device removals, if enough
missing devices have returned.