btrfs-check

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A fájlrendszer-ellenőrzőt a fájlrendszer szerkezeti integritásának ellenőrzésére és kérésre javításának megkísérlésére használják. Ajánlott a fájlrendszer leválasztása az ellenőrzés futtatása előtt, de lehetséges a csatlakoztatott fájlrendszer ellenőrzése is (lásd --force).

 

 

Man oldal kimenet

man btrfs-check
BTRFS-CHECK(8)                        Btrfs Manual                       BTRFS-CHECK(8)

NAME
       btrfs-check - check or repair a btrfs filesystem

SYNOPSIS
       btrfs check [options] <device>

DESCRIPTION
       The filesystem checker is used to verify structural integrity of a filesystem
       and attempt to repair it if requested. It is recommended to unmount the
       filesystem prior to running the check, but it is possible to start checking a
       mounted filesystem (see --force).

       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.

           Warning
           Do not use --repair unless you are advised to do so by a developer or an
           experienced user, and then only after having accepted that no fsck
           successfully repair all types of filesystem corruption. Eg. some other
           software or hardware bugs can fatally damage a volume.

       The structural integrity check verifies if internal filesystem objects or data
       structures satisfy the constraints, point to the right objects or are correctly
       connected together.

       There are several cross checks that can detect wrong reference counts of shared
       extents, backreferences, missing extents of inodes, directory and inode
       connectivity etc.

       The amount of memory required can be high, depending on the size of the
       filesystem, similarly the run time.

SAFE OR ADVISORY OPTIONS
       -b|--backup
           use 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, and is basically and
           offline scrub but does not repair data from spare copies.

       --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

       -Q|--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.

       --clear-space-cache v1|v2
           completely wipe all free space cache of given type

           For free space cache v1, the clear_cache kernel mount option only rebuilds
           the free space cache for block groups that are modified while the filesystem
           is mounted with that option. Thus, using this option with v1 makes it
           possible to actually clear the entire free space cache.

           For free space cache v2, the clear_cache kernel mount option destroys the
           entire free space cache. This option, with v2 provides an alternative method
           of clearing the free space cache that doesn’t require mounting the
           filesystem.

DANGEROUS OPTIONS
       --repair
           enable 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 consumption 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.

           Note
           lowmem mode does not work with --repair yet, and is still considered
           experimental.

       --force
           allow work on a mounted filesystem. Note that this should work fine on a
           quiescent or read-only mounted filesystem but may crash if the device is
           changed externally, eg. by the kernel module. Repair without mount checks is
           not supported right now.

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)

Btrfs v4.20.1                          01/23/2019                        BTRFS-CHECK(8)

 

 

Súgó kimenet

btrfs check --help
usage: btrfs check [options] <device>

    Check structural integrity of a filesystem (unmounted).

    Check structural integrity of an unmounted filesystem. Verify internal
    trees' consistency and item connectivity. In the repair mode try to
    fix the problems found. 
    WARNING: the repair mode is considered dangerous and should not be used
             without prior analysis of problems found on the filesystem.
    Options:
      starting point selection:
           -s|--super <superblock>     use this superblock copy
           -b|--backup                 use the first valid backup root copy
           -r|--tree-root <bytenr>     use the given bytenr for the tree root
           --chunk-root <bytenr>       use the given bytenr for the chunk tree root
      operation modes:
           --readonly                  run in read-only mode (default)
           --repair                    try to repair the filesystem
           --force                     skip mount checks, repair is not possible
           --mode <MODE>               allows choice of memory/IO trade-offs
                                       where MODE is one of:
                                       original - read inodes and extents to memory (requires
                                                  more memory, does less IO)
                                       lowmem   - try to use less memory but read blocks again
                                                  when needed (experimental)
      repair options:
           --init-csum-tree            create a new CRC tree
           --init-extent-tree          create a new extent tree
           --clear-space-cache v1|v2   clear space cache for v1 or v2
      check and reporting options:
           --check-data-csum           verify checksums of data blocks
           -Q|--qgroup-report          print a report on qgroup consistency
           -E|--subvol-extents <subvolid>
                                       print subvolume extents and sharing state
           -p|--progress               indicate progress

 

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