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BTRFS-CHECK(8) | Btrfs Manual | BTRFS-CHECK(8) |
NAME¶
btrfs-check - check or repair an unmounted btrfs filesystemSYNOPSIS¶
btrfs check [options] <device>DESCRIPTION¶
The filesystem checker is used to verify structural integrity of a filesystem and attempt to repair it if requested. The filesystem must be unmounted. By default, btrfs check will not modify the device but you can reaffirm that by the option --readonly. btrfsck is an alias of btrfs check command and is now deprecated.SAFE OR ADVISORY OPTIONS¶
-b|--backupuse the first valid set of backup roots stored in the
superblock
This can be combined with --super if some of the superblocks are
damaged.
--check-data-csum
verify checksums of data blocks
This expects that the filesystem is otherwise OK, so this is basically and
offline scrub but does not repair data from spare coipes.
--chunk-root <bytenr>
use the given offset bytenr for the chunk tree
root
-E|--subvol-extents <subvolid>
show extent state for the given subvolume
-p|--progress
indicate progress at various checking phases
--qgroup-report
verify qgroup accounting and compare against filesystem
accounting
-r|--tree-root <bytenr>
use the given offset bytenr for the tree
root
--readonly
(default) run in read-only mode, this option exists to
calm potential panic when users are going to run the checker
-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
This can be used to use a different starting point if some of the primary
superblock is damaged.
DANGEROUS OPTIONS¶
--repairenable the repair mode and attempt to fix problems where
possible
--init-csum-tree
create a new checksum tree and recalculate checksums in
all files
Note
Do not blindly use this option to fix checksum mismatch problems.
--init-extent-tree
build the extent tree from scratch
Note
Do not use unless you know what you’re doing.
--mode=MODE
select mode of operation regarding memory and IO
The MODE can be one of original and lowmem. The original
mode is mostly unoptimized regarding memory consumpption and can lead to
out-of-memory conditions on large filesystems. The possible workaround is to
export the block device over network to a machine with enough memory. The low
memory mode is supposed to address the memory consumption, at the cost of
increased IO when it needs to re-read blocks when needed. This may increase
run time.
EXIT STATUS¶
btrfs check 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-scrub(8), btrfs-rescue(8)10/02/2016 | Btrfs v4.7.3 |