NAME

       thin_check - validates thin provisioning metadata on a device or file

SYNOPSIS

       thin_check [options] {device|file}

DESCRIPTION

       thin_check   checks   thin   provisioning  metadata  created  by  the  device-mapper  thin
       provisioning target on a device or file.

       The tool cannot be run on live metadata unless the --metadata-snapshot option is used.

OPTIONS

       -q, --quiet
              Suppress output messages, return only exit code.

       -h, --help
              Print help and exit.

       -V, --version
              Output version information and exit.

       --super-block-only
              Only check the superblock.

       --skip-mappings
              Skip checking of the block mappings which make up the bulk of the metadata.

       --ignore-non-fatal-errors
              Will only return a non-zero exit code if it finds a fatal error.

           An example of a nonfatal error is an incorrect data block reference count
           causing a block to be considered allocated when it in fact isn't.  Ignoring
           errors for a long time is not advised, you really should be using
           thin_repair to fix them.

       --clear-needs-check-flag
              Clears the 'needs_check' flag in the superblock.

           The kernel may set a flag to force the pool to be checked before it's next
           activated.  Set this switch to clear the flag if the check is successful.
           If the metadata check failed, the flag is not cleared and a thin_repair run
           is needed to fix any issues. After thin_repair succeeded, you may run
           thin_check again.

       --metadata-snapshot, -m
              Check the metadata snapshot.

           This will check the devices tree and mappings in a metadata snapshot.
           The snap does not contain space maps, so these will not be checked.  This
           may be used on live metadata.

       --auto-repair
              Automatically repair any trivial issues found with the metadata.

           Currently only fixes metadata leaks.

       --override-mapping-root <block>
              Specify a mapping root to use.

           Don't use this.  This overrides what's specified in the superblock.  Only
           use this if you really understand the metadata format and are trying to
           recover damaged metadata.

EXAMPLE

       Analyses thin provisioning metadata on logical volume /dev/vg/metadata:

           $ thin_check /dev/vg/metadata

       The device must not be actively used by the target when running.

DIAGNOSTICS

       thin_check returns an exit code of 0 for success or 1 for error.

SEE ALSO

       thin_dump(8), thin_repair(8), thin_restore(8), thin_rmap(8), thin_metadata_size(8)

AUTHOR

       Joe Thornber <ejt@redhat.com>, Heinz Mauelshagen <heinzm@redhat.com>