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btrfs-select-super(8)
=====================
SYNOPSIS
--------
**btrfs-select-super** -s number <device>
DESCRIPTION
-----------
Destructively overwrite all copies of the superblock with a specified copy.
This helps in certain cases, for example when write barriers were disabled
during a power failure and not all superblocks were written, or if the primary
superblock is damaged, e.g. accidentally overwritten.
The filesystem specified by *device* must not be mounted.
.. note::
Prior to overwriting the primary superblock, please make sure that the
backup copies are valid!
To dump a superblock use the :command:`btrfs inspect-internal dump-super` command.
Then run the check (in the non-repair mode) using the command :command:`btrfs check -s`
where *-s* specifies the superblock copy to use.
Superblock copies exist in the following offsets on the device:
- primary: 64KiB (65536)
- 1st copy: 64MiB (67108864)
- 2nd copy: 256GiB (274877906944)
A superblock size is 4KiB (4096).
OPTIONS
-------
-s|--super <N>
use Nth superblock copy, valid values are 0 1 or 2 if the
respective superblock offset is within the device size
SEE ALSO
--------
:doc:`btrfs`
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