1.\" 2.\" CDDL HEADER START 3.\" 4.\" The contents of this file are subject to the terms of the 5.\" Common Development and Distribution License (the "License"). 6.\" You may not use this file except in compliance with the License. 7.\" 8.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9.\" or https://opensource.org/licenses/CDDL-1.0. 10.\" See the License for the specific language governing permissions 11.\" and limitations under the License. 12.\" 13.\" When distributing Covered Code, include this CDDL HEADER in each 14.\" file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15.\" If applicable, add the following below this CDDL HEADER, with the 16.\" fields enclosed by brackets "[]" replaced with your own identifying 17.\" information: Portions Copyright [yyyy] [name of copyright owner] 18.\" 19.\" CDDL HEADER END 20.\" 21.\" Copyright (c) 2007, Sun Microsystems, Inc. All Rights Reserved. 22.\" Copyright (c) 2012, 2018 by Delphix. All rights reserved. 23.\" Copyright (c) 2012 Cyril Plisko. All Rights Reserved. 24.\" Copyright (c) 2017 Datto Inc. 25.\" Copyright (c) 2018, 2021 George Melikov. All Rights Reserved. 26.\" Copyright 2017 Nexenta Systems, Inc. 27.\" Copyright (c) 2017 Open-E, Inc. All Rights Reserved. 28.\" 29.Dd June 22, 2023 30.Dt ZPOOL-SCRUB 8 31.Os 32. 33.Sh NAME 34.Nm zpool-scrub 35.Nd begin or resume scrub of ZFS storage pools 36.Sh SYNOPSIS 37.Nm zpool 38.Cm scrub 39.Op Fl s Ns | Ns Fl p 40.Op Fl w 41.Op Fl e 42.Ar pool Ns … 43. 44.Sh DESCRIPTION 45Begins a scrub or resumes a paused scrub. 46The scrub examines all data in the specified pools to verify that it checksums 47correctly. 48For replicated 49.Pq mirror, raidz, or draid 50devices, ZFS automatically repairs any damage discovered during the scrub. 51The 52.Nm zpool Cm status 53command reports the progress of the scrub and summarizes the results of the 54scrub upon completion. 55.Pp 56Scrubbing and resilvering are very similar operations. 57The difference is that resilvering only examines data that ZFS knows to be out 58of date 59.Po 60for example, when attaching a new device to a mirror or replacing an existing 61device 62.Pc , 63whereas scrubbing examines all data to discover silent errors due to hardware 64faults or disk failure. 65.Pp 66When scrubbing a pool with encrypted filesystems the keys do not need to be 67loaded. 68However, if the keys are not loaded and an unrepairable checksum error is 69detected the file name cannot be included in the 70.Nm zpool Cm status Fl v 71verbose error report. 72.Pp 73Because scrubbing and resilvering are I/O-intensive operations, ZFS only allows 74one at a time. 75.Pp 76A scrub is split into two parts: metadata scanning and block scrubbing. 77The metadata scanning sorts blocks into large sequential ranges which can then 78be read much more efficiently from disk when issuing the scrub I/O. 79.Pp 80If a scrub is paused, the 81.Nm zpool Cm scrub 82resumes it. 83If a resilver is in progress, ZFS does not allow a scrub to be started until the 84resilver completes. 85.Pp 86Note that, due to changes in pool data on a live system, it is possible for 87scrubs to progress slightly beyond 100% completion. 88During this period, no completion time estimate will be provided. 89. 90.Sh OPTIONS 91.Bl -tag -width "-s" 92.It Fl s 93Stop scrubbing. 94.It Fl p 95Pause scrubbing. 96Scrub pause state and progress are periodically synced to disk. 97If the system is restarted or pool is exported during a paused scrub, 98even after import, scrub will remain paused until it is resumed. 99Once resumed the scrub will pick up from the place where it was last 100checkpointed to disk. 101To resume a paused scrub issue 102.Nm zpool Cm scrub 103or 104.Nm zpool Cm scrub 105.Fl e 106again. 107.It Fl w 108Wait until scrub has completed before returning. 109.It Fl e 110Only scrub files with known data errors as reported by 111.Nm zpool Cm status Fl v . 112The pool must have been scrubbed at least once with the 113.Sy head_errlog 114feature enabled to use this option. 115Error scrubbing cannot be run simultaneously with regular scrubbing or 116resilvering, nor can it be run when a regular scrub is paused. 117.El 118.Sh EXAMPLES 119.Ss Example 1 120Status of pool with ongoing scrub: 121.sp 122.Bd -literal -compact 123.No # Nm zpool Cm status 124 ... 125 scan: scrub in progress since Sun Jul 25 16:07:49 2021 126 403M / 405M scanned at 100M/s, 68.4M / 405M issued at 10.0M/s 127 0B repaired, 16.91% done, 00:00:04 to go 128 ... 129.Ed 130.Pp 131Where metadata which references 403M of file data has been 132scanned at 100M/s, and 68.4M of that file data has been 133scrubbed sequentially at 10.0M/s. 134.Sh PERIODIC SCRUB 135On machines using systemd, scrub timers can be enabled on per-pool basis. 136.Nm weekly 137and 138.Nm monthly 139timer units are provided. 140.Bl -tag -width Ds 141.It Xo 142.Xc 143.Nm systemctl 144.Cm enable 145.Cm zfs-scrub-\fIweekly\fB@\fIrpool\fB.timer 146.Cm --now 147.It Xo 148.Xc 149.Nm systemctl 150.Cm enable 151.Cm zfs-scrub-\fImonthly\fB@\fIotherpool\fB.timer 152.Cm --now 153.El 154. 155.Sh SEE ALSO 156.Xr systemd.timer 5 , 157.Xr zpool-iostat 8 , 158.Xr zpool-resilver 8 , 159.Xr zpool-status 8 160