Provided by: btrfs-tools_4.4-1_amd64 bug

NAME

       btrfs-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-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.

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)

       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 mounting.

       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.

       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>.

           Options

           -z
               Reset stats to zero after reading them.

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

           Options

           -b|--raw
               raw numbers in bytes, without the B suffix

           -h|--human-readable
               print human friendly numbers, base 1024, this is the default

           -H
               print human friendly numbers, base 1000

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

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

           -k|--kbytes
               show sizes in KiB, or kB with --si

           -m|--mbytes
               show sizes in MiB, or MB with --si

           -g|--gbytes
               show sizes in GiB, or GB with --si

           -t|--tbytes
               show sizes in TiB, or TB with --si

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

EXIT STATUS

       btrfs device returns a zero exit 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 ALSO

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