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.\" $FreeBSD$ 27.\" 28.Dd April 18, 2020 29.Dt ZFSD 8 30.Os 31.Sh NAME 32.Nm zfsd 33.Nd ZFS fault management daemon 34.Sh SYNOPSIS 35.Nm 36.Op Fl d 37.Sh DESCRIPTION 38.Nm 39attempts to resolve ZFS faults that the kernel can't resolve by itself. 40It listens to 41.Xr devctl 4 42events, which are how the kernel notifies userland of events such as I/O 43errors and disk removals. 44.Nm 45attempts to resolve these faults by activating or deactivating hot spares 46and onlining offline vdevs. 47.Pp 48The following options are available: 49.Bl -tag -width indent 50.It Fl d 51Run in the foreground instead of daemonizing. 52.El 53.Pp 54System administrators never interact with 55.Nm 56directly. 57Instead, they control its behavior indirectly through zpool configuration. 58There are two ways to influence 59.Nm : 60assigning hotspares and setting pool properties. 61Currently, only the 62.Em autoreplace 63property has any effect. 64See 65.Xr zpool 8 66for details. 67.Pp 68.Nm 69will attempt to resolve the following types of fault: 70.Bl -tag -width a 71.It device removal 72When a leaf vdev disappears, 73.Nm 74will activate any available hotspare. 75.It device arrival 76When a new GEOM device appears, 77.Nm 78will attempt to read its ZFS label, if any. 79If it matches a previously removed vdev on an active pool, 80.Nm 81will online it. 82Once resilvering completes, any active hotspare will detach automatically. 83.Pp 84If the new device has no ZFS label but its physical path matches the 85physical path of a previously removed vdev on an active pool, and that 86pool has the autoreplace property set, then 87.Nm 88will replace the missing vdev with the newly arrived device. 89Once resilvering completes, any active hotspare will detach automatically. 90.It vdev degrade or fault events 91If a vdev becomes degraded or faulted, 92.Nm 93will activate any available hotspare. 94.It I/O errors 95If a leaf vdev generates more than 50 I/O errors in a 60 second period, then 96.Nm 97will mark that vdev as 98.Em FAULTED . 99ZFS will no longer issue any I/Os to it. 100.Nm 101will activate a hotspare if one is available. 102.It Checksum errors 103If a leaf vdev generates more than 50 checksum errors in a 60 second 104period, then 105.Nm 106will mark that vdev as 107.Em DEGRADED . 108ZFS will still use it, but zfsd will activate a spare anyway. 109.It Spare addition 110If the system administrator adds a hotspare to a pool that is already degraded, 111.Nm 112will activate the spare. 113.It Resilver complete 114.Nm 115will detach any hotspare once a permanent replacement finishes resilvering. 116.It Physical path change 117If the physical path of an existing disk changes, 118.Nm 119will attempt to replace any missing disk with the same physical path, 120if its pool's autoreplace property is set. 121.El 122.Pp 123.Nm 124will log interesting events and its actions to syslog with facility 125.Em daemon 126and identity 127.Op zfsd . 128.El 129.Sh FILES 130.Bl -tag -width a -compact 131.It Pa /var/db/zfsd/cases 132When 133.Nm 134exits, it serializes any unresolved casefiles here, 135then reads them back in when next it starts up. 136.El 137.Sh SEE ALSO 138.Xr devctl 4 , 139.Xr zpool 8 140.Sh HISTORY 141.Nm 142first appeared in 143.Fx 11.0 . 144.Sh AUTHORS 145.Nm 146was originally written by 147.An Justin Gibbs Aq Mt gibbs@FreeBSD.org 148and 149.An Alan Somers Aq Mt asomers@FreeBSD.org 150.Sh TODO 151In the future, 152.Nm 153should be able to resume a pool that became suspended due to device 154removals, if enough missing devices have returned. 155