1.\"- 2.\" Copyright (c) 2016 Allan Jude 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.Dd April 18, 2020 27.Dt ZFSD 8 28.Os 29.Sh NAME 30.Nm zfsd 31.Nd ZFS fault management daemon 32.Sh SYNOPSIS 33.Nm 34.Op Fl d 35.Sh DESCRIPTION 36.Nm 37attempts to resolve ZFS faults that the kernel can't resolve by itself. 38It listens to 39.Xr devctl 4 40events, which are how the kernel notifies userland of events such as I/O 41errors and disk removals. 42.Nm 43attempts to resolve these faults by activating or deactivating hot spares 44and onlining offline vdevs. 45.Pp 46The following options are available: 47.Bl -tag -width indent 48.It Fl d 49Run in the foreground instead of daemonizing. 50.El 51.Pp 52System administrators never interact with 53.Nm 54directly. 55Instead, they control its behavior indirectly through zpool configuration. 56There are two ways to influence 57.Nm : 58assigning hotspares and setting pool properties. 59Currently, only the 60.Em autoreplace 61property has any effect. 62See 63.Xr zpool 8 64for details. 65.Pp 66.Nm 67will attempt to resolve the following types of fault: 68.Bl -tag -width a 69.It device removal 70When a leaf vdev disappears, 71.Nm 72will activate any available hotspare. 73.It device arrival 74When a new GEOM device appears, 75.Nm 76will attempt to read its ZFS label, if any. 77If it matches a previously removed vdev on an active pool, 78.Nm 79will online it. 80Once resilvering completes, any active hotspare will detach automatically. 81.Pp 82If the new device has no ZFS label but its physical path matches the 83physical path of a previously removed vdev on an active pool, and that 84pool has the autoreplace property set, then 85.Nm 86will replace the missing vdev with the newly arrived device. 87Once resilvering completes, any active hotspare will detach automatically. 88.It vdev degrade or fault events 89If a vdev becomes degraded or faulted, 90.Nm 91will activate any available hotspare. 92.It I/O errors 93If a leaf vdev generates more than 50 I/O errors in a 60 second period, then 94.Nm 95will mark that vdev as 96.Em FAULTED . 97ZFS will no longer issue any I/Os to it. 98.Nm 99will activate a hotspare if one is available. 100.It Checksum errors 101If a leaf vdev generates more than 50 checksum errors in a 60 second 102period, then 103.Nm 104will mark that vdev as 105.Em DEGRADED . 106ZFS will still use it, but zfsd will activate a spare anyway. 107.It Spare addition 108If the system administrator adds a hotspare to a pool that is already degraded, 109.Nm 110will activate the spare. 111.It Resilver complete 112.Nm 113will detach any hotspare once a permanent replacement finishes resilvering. 114.It Physical path change 115If the physical path of an existing disk changes, 116.Nm 117will attempt to replace any missing disk with the same physical path, 118if its pool's autoreplace property is set. 119.El 120.Pp 121.Nm 122will log interesting events and its actions to syslog with facility 123.Em daemon 124and identity 125.Op zfsd . 126.El 127.Sh FILES 128.Bl -tag -width a -compact 129.It Pa /var/db/zfsd/cases 130When 131.Nm 132exits, it serializes any unresolved casefiles here, 133then reads them back in when next it starts up. 134.El 135.Sh SEE ALSO 136.Xr devctl 4 , 137.Xr zpool 8 138.Sh HISTORY 139.Nm 140first appeared in 141.Fx 11.0 . 142.Sh AUTHORS 143.Nm 144was originally written by 145.An Justin Gibbs Aq Mt gibbs@FreeBSD.org 146and 147.An Alan Somers Aq Mt asomers@FreeBSD.org 148.Sh TODO 149In the future, 150.Nm 151should be able to resume a pool that became suspended due to device 152removals, if enough missing devices have returned. 153