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