1BTRFS-SELECT-SUPER(8)            Btrfs Manual            BTRFS-SELECT-SUPER(8)
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NAME

6       btrfs-select-super - overwrite primary superblock with a backup copy
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SYNOPSIS

9       btrfs-select-super -s number <device>
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DESCRIPTION

12       Destructively overwrite all copies of the superblock with a specified
13       copy. This helps in certain cases, for example when write barriers were
14       disabled during a power failure and not all superblocks were written,
15       or if the primary superblock is damaged, eg. accidentally overwritten.
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17       The filesystem specified by device must not be mounted.
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19           Note
20           Prior to overwriting the primary superblock, please make sure that
21           the backup copies are valid!
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23       To dump a superblock use the btrfs inspect-internal dump-super command.
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25       Then run the check (in the non-repair mode) using the command btrfs
26       check -s where -s specifies the superblock copy to use.
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28       Superblock copies exist in the following offsets on the device:
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30       ·   primary: 64KiB (65536)
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32       ·   1st copy: 64MiB (67108864)
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34       ·   2nd copy: 256GiB (274877906944)
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36       A superblock size is 4KiB (4096).
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OPTIONS

39       -s|--super <superblock>
40           use 'superblock’th superblock copy, valid values are 0 1 or 2 if
41           the respective superblock offset is within the device size
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SEE ALSO

44       btrfs-inspect-internal(8), btrfsck check(8)
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48Btrfs v5.10                       01/18/2021             BTRFS-SELECT-SUPER(8)
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