'\" t
.\"     Title: btrfs-device
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.76.1 <http://docbook.sf.net/>
.\"      Date: 06/20/2015
.\"    Manual: Btrfs Manual
.\"    Source: Btrfs v3.17
.\"  Language: English
.\"
.TH "BTRFS\-DEVICE" "8" "06/20/2015" "Btrfs v3\&.17" "Btrfs Manual"
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.SH "NAME"
btrfs-device \- control btrfs devices
.SH "SYNOPSIS"
.sp
\fBbtrfs device\fR \fI<subcommand>\fR \fI<args>\fR
.SH "DESCRIPTION"
.sp
\fBbtrfs device\fR is used to control the btrfs devices, since btrfs can be used across several devices, \fBbtrfs device\fR is used for multiple device management\&.
.SH "DEVICE MANAGEMENT"
.sp
Btrfs filesystem is capable to manage multiple devices\&.
.sp
Btrfs filesystem uses different profiles to manage different RAID level, and use balance to rebuild chunks, also devices can be added/removed/replace online\&.
.PP
Profile
.RS 4
Btrfs filesystem uses data/metadata profiles to manage allocation/duplication mechanism\&.

Profiles like RAID level can be assigned to data and metadata separately\&.
.sp
See
\fBmkfs\&.btrfs\fR(8) for more details\&.
.RE
.PP
RAID level
.RS 4
Btrfs filesystem supports most of the standard RAID level: 0/1/5/6/10\&.

RAID levels can be assigned at mkfs time or online\&.
.sp
See
\fBmkfs\&.btrfs\fR(8) for mkfs time RAID level assign and
\fBbtrfs\-balance\fR(8) for online RAID level assign\&.
.if n \{\
.sp
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.RS 4
.it 1 an-trap
.nr an-no-space-flag 1
.nr an-break-flag 1
.br
.ps +1
\fBNote\fR
.ps -1
.br
Since btrfs is under heavy development especially the RAID5/6 support, it is
\fBhighly\fR
recommended to read the follow btrfs wiki page to get more updated details on RAID5/6:

\m[blue]\fBhttps://btrfs\&.wiki\&.kernel\&.org/index\&.php/RAID56\fR\m[]
.sp .5v
.RE
.RE
.PP
Balance
.RS 4

\fBbtrfs\-balance\fR(8) subcommand can be used to balance or rebuild chunks to the desired profile\&.
.sp
Due to the fact that balance can rebuild/recovery chunks according to its RAID duplication if possible, so when using RAID1/5/6/10 with some devices failed and you just added a new device to btrfs using
\fBbtrfs\-device\fR(8), you should run
\fBbtrfs\-balance\fR(8) to rebuild the chunks\&.
.sp
See
\fBbtrfs\-balance\fR(8) for more details\&.
.RE
.PP
Device add/remove/replace
.RS 4
Device can be added/removed using
\fBbtrfs\-replace\fR(8) subcommand and replaced using
\fBbtrfs\-replace\fR(8)\&.
.sp
When device is removed or replaced, btrfs will do the chunk rebuild if needed\&.
.sp
See
\fBbtrfs\-replace\fR(8) and this man page for more details\&.
.RE
.SH "SUBCOMMAND"
.PP
\fBadd\fR [\-Kf] \fI<dev>\fR [\fI<dev>\fR\&...] \fI<path>\fR
.RS 4
Add device(s) to the filesystem identified by
\fI<path>\fR\&.
.sp
If applicable, a whole device discard (TRIM) operation is performed\&.
.sp
\fBOptions\fR
.PP
\-K|\-\-nodiscard
.RS 4
do not perform discard by default
.RE
.PP
\-f|\-\-force
.RS 4
force overwrite of existing filesystem on the given disk(s)
.RE
.RE
.PP
\fBdelete\fR \fI<dev>\fR [\fI<dev>\fR\&...] \fI<path>\fR
.RS 4
Remove device(s) from a filesystem identified by
\fI<path>\fR\&.
.RE
.PP
\fBscan\fR [(\-\-all\-devices|\-d)|\fI<device>\fR [\fI<device>\fR\&...]]
.RS 4
Scan devices for a btrfs filesystem\&.
.sp
If one or more devices are passed, these are scanned for a btrfs filesystem\&. If no devices are passed, btrfs uses block devices containing btrfs filesystem as listed by blkid\&. Finally, if
\fI\-\-all\-devices\fR
or
\fI\-d\fR
is passed, all the devices under /dev are scanned\&.
.RE
.PP
\fBready\fR \fI<device>\fR
.RS 4
Check device to see if it has all of it\(cqs devices in cache for mounting\&.
.RE
.PP
\fBstats\fR [\-z] \fI<path>\fR|\fI<device>\fR
.RS 4
Read and print the device IO stats for all devices of the filesystem identified by
\fI<path>\fR
or for a single
\fI<device>\fR\&.
.sp
\fBOptions\fR
.PP
\-z
.RS 4
Reset stats to zero after reading them\&.
.RE
.RE
.SH "EXIT STATUS"
.sp
\fBbtrfs device\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), \fBbtrfs\-replace\fR(8), \fBbtrfs\-balance\fR(8)