# phpman > man > BTRFS-SELECT-SUPER(8)

[BTRFS-SELECT-SUPER(8)](https://www.chedong.com/phpMan.php/man/BTRFS-SELECT-SUPER/8/markdown)                       Btrfs Manual                       [BTRFS-SELECT-SUPER(8)](https://www.chedong.com/phpMan.php/man/BTRFS-SELECT-SUPER/8/markdown)



## NAME
       btrfs-select-super - overwrite primary superblock with a backup copy

## 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, eg. 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 **btrfs** **inspect-internal** **dump-super** command.

       Then run the check (in the non-repair mode) using the 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 _<superblock>_
           use 'superblock’th superblock copy, valid values are 0 1 or 2 if the respective
           superblock offset is within the device size

## SEE ALSO
       [**btrfs-inspect-internal**(8)](https://www.chedong.com/phpMan.php/man/btrfs-inspect-internal/8/markdown), **btrfsck** [**check**(8)](https://www.chedong.com/phpMan.php/man/check/8/markdown)



Btrfs v5.16.2                                02/16/2022                        [BTRFS-SELECT-SUPER(8)](https://www.chedong.com/phpMan.php/man/BTRFS-SELECT-SUPER/8/markdown)