Provided by: btrfs-tools_4.4-1ubuntu1.1_amd64 
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 [-Bfr] <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 is 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>.
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 containing a valid btrfs
filesystem.
A valid filesystem is assumed if a btrfs superblock is found which contains a correct checksum.
Devices which are currently mounted are never allowed to be used as the <targetdev>.
-B
no background replace.
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 canceled)
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 btrfs wiki http://btrfs.wiki.kernel.org for further details.
SEE ALSO
mkfs.btrfs(8), btrfs-device(8),