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31 .Nd ZFS fault management daemon
37 attempts to resolve ZFS faults that the kernel can't resolve by itself.
40 events, which are how the kernel notifies userland of events such as I/O
41 errors and disk removals.
43 attempts to resolve these faults by activating or deactivating hot spares
44 and onlining offline vdevs.
46 The following options are available:
47 .Bl -tag -width indent
49 Run in the foreground instead of daemonizing.
52 System administrators never interact with
55 Instead, they control its behavior indirectly through zpool configuration.
56 There are two ways to influence
58 assigning hotspares and setting pool properties.
61 property has any effect.
67 will attempt to resolve the following types of fault:
70 When a leaf vdev disappears,
72 will activate any available hotspare.
74 When a new GEOM device appears,
76 will attempt to read its ZFS label, if any.
77 If it matches a previously removed vdev on an active pool,
80 Once resilvering completes, any active hotspare will detach automatically.
82 If the new device has no ZFS label but its physical path matches the
83 physical path of a previously removed vdev on an active pool, and that
84 pool has the autoreplace property set, then
86 will replace the missing vdev with the newly arrived device.
87 Once resilvering completes, any active hotspare will detach automatically.
88 .It vdev degrade or fault events
89 If a vdev becomes degraded or faulted,
91 will activate any available hotspare.
93 If a leaf vdev generates more than 50 I/O errors in a 60 second period, then
95 will mark that vdev as
97 ZFS will no longer issue any I/Os to it.
99 will activate a hotspare if one is available.
101 If a leaf vdev generates more than 50 checksum errors in a 60 second
104 will mark that vdev as
106 ZFS will still use it, but zfsd will activate a spare anyway.
108 If the system administrator adds a hotspare to a pool that is already degraded,
110 will activate the spare.
111 .It Resilver complete
113 will detach any hotspare once a permanent replacement finishes resilvering.
114 .It Physical path change
115 If the physical path of an existing disk changes,
117 will attempt to replace any missing disk with the same physical path,
118 if its pool's autoreplace property is set.
122 will log interesting events and its actions to syslog with facility
128 .Bl -tag -width a -compact
129 .It Pa /var/db/zfsd/cases
132 exits, it serializes any unresolved casefiles here,
133 then reads them back in when next it starts up.
144 was originally written by
145 .An Justin Gibbs Aq Mt gibbs@FreeBSD.org
147 .An Alan Somers Aq Mt asomers@FreeBSD.org
151 should be able to resume a pool that became suspended due to device
152 removals, if enough missing devices have returned.