BTRFS-REPLACE(8) Btrfs Manual BTRFS-REPLACE(8)
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
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.
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
Example 1. 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 btrfs wiki
http://btrfs.wiki.kernel.org for further details.
SEE ALSO
mkfs.btrfs(8), btrfs-device(8), btrfs-filesystem(8),
Btrfs v5.7 07/02/2020 BTRFS-REPLACE(8)