'\" t
.\"     Title: btrfs-scrub
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
.\"      Date: 11/22/2014
.\"    Manual: Btrfs Manual
.\"    Source: Btrfs v3.17
.\"  Language: English
.\"
.TH "BTRFS\-SCRUB" "8" "11/22/2014" "Btrfs v3\&.17" "Btrfs Manual"
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.SH "NAME"
btrfs-scrub \- scrub btrfs filesystem
.SH "SYNOPSIS"
.sp
\fBbtrfs scrub\fR \fI<subcommand>\fR \fI<args>\fR
.SH "DESCRIPTION"
.sp
\fBbtrfs scrub\fR is used to scrub a btrfs filesystem, which will reading all data from all disks and verifying checksums\&.
.SH "SUBCOMMAND"
.PP
\fBstart\fR [\-BdqrRf] [\-c \fI<ioprio_class>\fR \-n \fI<ioprio_classdata>\fR] \fI<path>\fR|\fI<device>\fR
.RS 4
Start a scrub on all devices of the filesystem identified by
\fI<path>\fR
or on a single
\fI<device>\fR\&. If a scrub is already running, the new one fails\&.
.sp
Without options, scrub is started as a background process\&. Progress can be obtained with the
\fBscrub status\fR
command\&. Scrubbing involves reading all data from all disks and verifying checksums\&. Errors are corrected along the way if possible\&.
.sp
The default IO priority of scrub is the idle class\&. The priority can be configured similar to the
\fBionice\fR(1) syntax using
\fI\-c\fR
and
\fI\-n\fR
options\&.
.sp
\fBOptions\fR
.PP
\-B
.RS 4
Do not background and print scrub statistics when finished\&.
.RE
.PP
\-d
.RS 4
Print separate statistics for each device of the filesystem (\-B only)\&.
.RE
.PP
\-q
.RS 4
Quiet\&. Omit error messages and statistics\&.
.RE
.PP
\-r
.RS 4
Read only mode\&. Do not attempt to correct anything\&.
.RE
.PP
\-R
.RS 4
Raw print mode\&. Print full data instead of summary\&.
.RE
.PP
\-c \fI<ioprio_class>\fR
.RS 4
Set IO priority class (see ionice (1) manpage)\&.
.RE
.PP
\-n \fI<ioprio_classdata>\fR
.RS 4
Set IO priority classdata (see
\fBionice\fR(1) manpage)\&.
.RE
.PP
\-f
.RS 4
Force starting new scrub even if a scrub is already running\&. This is useful when scrub stat record file is damaged\&.
.RE
.RE
.PP
\fBcancel\fR \fI<path>\fR|\fI<device>\fR
.RS 4
If a scrub is running on the filesystem identified by
\fI<path>\fR, cancel it\&.
.sp
Progress is saved in the scrub progress file and scrubbing can be resumed later using the scrub resume command\&. If a
\fI<device>\fR
is given, the corresponding filesystem is found and scrub cancel behaves as if it was called on that filesystem\&.
.RE
.PP
\fBresume\fR [\-BdqrR] [\-c \fI<ioprio_class>\fR \-n \fI<ioprio_classdata>\fR] \fI<path>\fR|\fI<device>\fR
.RS 4
Resume a canceled or interrupted scrub cycle on the filesystem identified by
\fI<path>\fR
or on a given
\fI<device>\fR\&.
.sp
Does not start a new scrub if the last scrub finished successfully\&.
.sp
\fBOptions\fR
.sp
see
\fBscrub start\fR\&.
.RE
.PP
\fBstatus\fR [\-d] \fI<path>\fR|\fI<device>\fR
.RS 4
Show status of a running scrub for the filesystem identified by
\fI<path>\fR
or for the specified
\fI<device>\fR\&.
.sp
If no scrub is running, show statistics of the last finished or canceled scrub for that filesystem or device\&.
.sp
\fBOptions\fR
.PP
\-d
.RS 4
Print separate statistics for each device of the filesystem\&.
.RE
.RE
.SH "EXIT STATUS"
.sp
\fBbtrfs scrub\fR returns a zero exit status if it succeeds\&. Non zero is returned in case of failure\&.
.SH "AVAILABILITY"
.sp
\fBbtrfs\fR is part of btrfs\-progs\&. Please refer to the btrfs wiki \m[blue]\fBhttp://btrfs\&.wiki\&.kernel\&.org\fR\m[] for further details\&.
.SH "SEE ALSO"
.sp
\fBmkfs\&.btrfs\fR(8),