BTRFS-DEVICE(8) Btrfs Manual BTRFS-DEVICE(8)NAMEbtrfs-device - control btrfs devices
SYNOPSIS
btrfs device <subcommand> <args>
DESCRIPTION
btrfs device is used to control the btrfs devices, since btrfs can be
used across several devices, btrfs device is used for multiple device
management.
DEVICE MANAGEMENT
Btrfs filesystem is capable to manage multiple devices.
Btrfs filesystem uses different profiles to manage different RAID
level, and use balance to rebuild chunks, also devices can be
added/removed/replace online.
Profile
Btrfs filesystem uses data/metadata profiles to manage
allocation/duplication mechanism.
Profiles like RAID level can be assigned to data and metadata
separately.
See mkfs.btrfs(8) for more details.
RAID level
Btrfs filesystem supports most of the standard RAID level:
0/1/5/6/10.
RAID levels can be assigned at mkfs time or online.
See mkfs.btrfs(8) for mkfs time RAID level assign and
btrfs-balance(8) for online RAID level assign.
Note
Since btrfs is under heavy development especially the RAID5/6
support, it is highly recommended to read the follow btrfs wiki
page to get more updated details on RAID5/6:
https://btrfs.wiki.kernel.org/index.php/RAID56
Balance
btrfs-balance(8) subcommand can be used to balance or rebuild
chunks to the desired profile.
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 btrfs-device(8), you should run btrfs-balance(8) to rebuild
the chunks.
See btrfs-balance(8) for more details.
Device add/remove/replace
Device can be added/removed using btrfs-replace(8) subcommand and
replaced using btrfs-replace(8).
When device is removed or replaced, btrfs will do the chunk rebuild
if needed.
See btrfs-replace(8) and this man page for more details.
SUBCOMMAND
add [-Kf] <dev> [<dev>...] <path>
Add device(s) to the filesystem identified by <path>.
If applicable, a whole device discard (TRIM) operation is
performed.
Options
-K|--nodiscard
do not perform discard by default
-f|--force
force overwrite of existing filesystem on the given disk(s)
delete <dev> [<dev>...] <path>
Remove device(s) from a filesystem identified by <path>.
scan [(--all-devices|-d)|<device> [<device>...]]
Scan devices for a btrfs filesystem.
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
--all-devices or -d is passed, all the devices under /dev are
scanned.
ready <device>
Check device to see if it has all of it’s devices in cache for
mounting.
stats [-z] <path>|<device>
Read and print the device IO stats for all devices of the
filesystem identified by <path> or for a single <device>.
Options
-z
Reset stats to zero after reading them.
EXIT STATUS
btrfs device returns a zero exist status if it succeeds. Non zero is
returned in case of failure.
AVAILABILITY
btrfs is part of btrfs-progs. Please refer to the btrfs wiki
http://btrfs.wiki.kernel.org for further details.
SEE ALSOmkfs.btrfs(8), btrfs-replace(8), btrfs-balance(8)Btrfs v3.14.2 05/30/2014 BTRFS-DEVICE(8)
