Provided by: btrfs-progs_6.2-1_amd64 bug

NAME

       btrfs-replace - replace devices managed by btrfs with other device

SYNOPSIS

       btrfs replace <subcommand> <args>

DESCRIPTION

       btrfs replace is used to replace btrfs managed devices with other device.

SUBCOMMAND

       cancel <mount_point>
              Cancel a running device replace operation.

       start [options] <srcdev>|<devid> <targetdev> <path>
              Replace device of a btrfs filesystem.

              On  a  live  filesystem, duplicate the data to the target device which is currently
              stored on the source device.  If the source device is not available anymore, or  if
              the  -r option is set, the data is built only using the RAID redundancy mechanisms.
              After  completion  of  the  operation,  the  source  device  is  removed  from  the
              filesystem.   If the srcdev is a numerical value, it is assumed to be the device id
              of the filesystem which is mounted at path, otherwise it is the path to the  source
              device.  If the source device is disconnected, from the system, you have to use the
              devid parameter format.  The targetdev needs to be same size  or  larger  than  the
              srcdev.

              NOTE:
                 The  filesystem  has  to  be  resized to fully take advantage of a larger target
                 device; this can be achieved with btrfs filesystem resize <devid>:max /path

              Options

              -r     only read from srcdev if no other zero-defect mirror exists.   (enable  this
                     if your drive has lots of read errors, the access would be very slow)

              -f     force  using  and  overwriting targetdev even if it looks like it contains a
                     valid btrfs filesystem.

                     A valid filesystem is assumed if a btrfs superblock is found which  contains
                     a  correct checksum. Devices that are currently mounted are never allowed to
                     be used as the targetdev.

              -B     no background replace.

              --enqueue
                     wait if there's another exclusive operation running, otherwise continue

              -K|--nodiscard
                     Do not perform whole device TRIM operation on devices that  are  capable  of
                     that.   This  does  not affect discard/trim operation when the filesystem is
                     mounted.  Please see the mount option discard for that in btrfs(5).

       status [-1] <mount_point>
              Print status and progress information of a running device replace operation.

              Options

              -1     print once  instead  of  print  continuously  until  the  replace  operation
                     finishes (or is cancelled)

EXAMPLES

   Replacing an online drive with a bigger one
       Given the following filesystem mounted at /mnt/my-vault

          Label: 'MyVault'  uuid: ae20903e-b72d-49ba-b944-901fc6d888a1
                  Total devices 2 FS bytes used 1TiB
                  devid    1 size 1TiB used 500.00GiB path /dev/sda
                  devid    2 size 1TiB used 500.00GiB path /dev/sdb

       In  order  to replace /dev/sda (devid 1) with a bigger drive located at /dev/sdc you would
       run the following:

          btrfs replace start 1 /dev/sdc /mnt/my-vault/

       You can monitor progress via:

          btrfs replace status /mnt/my-vault/

       After the replacement is complete, as per the docs at btrfs-filesystem(8) in order to  use
       the entire storage space of the new drive you need to run:

          btrfs filesystem resize 1:max /mnt/my-vault/

EXIT STATUS

       btrfs  replace  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    documentation    at
       https://btrfs.readthedocs.io or wiki http://btrfs.wiki.kernel.org for further information.

SEE ALSO

       btrfs-device(8), btrfs-filesystem(8), mkfs.btrfs(8)