Provided by: btrfs-tools_4.4-1_i386 bug


       btrfs-device - control btrfs devices


       btrfs device <subcommand> <args>


       btrfs device is used to control the btrfs devices, since btrfs can be
       used across several devices, btrfs device is used for multiple device


       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.

           Btrfs filesystem uses data/metadata profiles to manage
           allocation/duplication mechanism.

           Profiles like RAID level can be assigned to data and metadata

           See mkfs.btrfs(8) for more details.

       RAID level
           Btrfs filesystem supports most of the standard RAID level:

           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.

               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:

           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-device(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) man page for more details on device replace.


       add [-Kf] <dev> [<dev>...] <path>
           Add device(s) to the filesystem identified by <path>.

           If applicable, a whole device discard (TRIM) operation is


               do not perform discard by default

               force overwrite of existing filesystem on the given disk(s)

       remove <dev> [<dev>...] <path>
           Remove device(s) from a filesystem identified by <path>.

       delete <dev> [<dev>...] <path>
           Alias of remove kept for backwards compatability

       ready <device>
           Check device to see if it has all of it’s devices in cache for

       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

       stats [-z] <path>|<device>
           Read and print the device IO stats for all mounted devices of the
           filesystem identified by <path> or for a single <device>.


               Reset stats to zero after reading them.

       usage [options] <path> [<path>...]
           Show detailed information about internal allocations in devices.


               raw numbers in bytes, without the B suffix

               print human friendly numbers, base 1024, this is the default

               print human friendly numbers, base 1000

               select the 1024 base for the following options, according to
               the IEC standard

               select the 1000 base for the following options, according to
               the SI standard

               show sizes in KiB, or kB with --si

               show sizes in MiB, or MB with --si

               show sizes in GiB, or GB with --si

               show sizes in TiB, or TB with --si

       If conflicting options are passed, the last one takes precedence.


       btrfs device returns a zero exit status if it succeeds. Non zero is
       returned in case of failure.


       btrfs is part of btrfs-progs. Please refer to the btrfs wiki for further details.


       mkfs.btrfs(8), btrfs-replace(8), btrfs-balance(8)