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