xfs_scrub(8) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPTIMIZATIONS | REPAIRS | EXIT CODE | CAVEATS | SEE ALSO | COLOPHON

xfs_scrub(8)             System Manager's Manual            xfs_scrub(8)

NAME         top

       xfs_scrub - check and repair the contents of a mounted XFS
       filesystem

SYNOPSIS         top

       xfs_scrub [ -abCemnTvx ] mount-point
       xfs_scrub -V

DESCRIPTION         top

       xfs_scrub attempts to check and repair all metadata in a mounted
       XFS filesystem.

       WARNING!  This program is EXPERIMENTAL, which means that its
       behavior and interface could change at any time!

       xfs_scrub asks the kernel to scrub all metadata objects in the
       filesystem.  Metadata records are scanned for obviously bad
       values and then cross-referenced against other metadata.  The
       goal is to establish a reasonable confidence about the
       consistency of the overall filesystem by examining the
       consistency of individual metadata records against the other
       metadata in the filesystem.  Damaged metadata can be rebuilt from
       other metadata if there exists redundant data structures which
       are intact.

       Filesystem corruption and optimization opportunities will be
       logged to the standard error stream.  Enabling verbose mode will
       increase the amount of status information sent to the output.

       If the kernel scrub reports that metadata needs repairs or
       optimizations and the user does not pass -n on the command line,
       this program will ask the kernel to make the repairs and to
       perform the optimizations.  See the sections about optimizations
       and repairs for a list of optimizations and repairs known to this
       program.  The kernel may not support repairing or optimizing the
       filesystem.  If this is the case, the filesystem must be
       unmounted and xfs_repair(8) run on the filesystem to fix the
       problems.

OPTIONS         top

       -a errors
              Abort if more than this many errors are found on the
              filesystem.

       -b     Run in background mode.  If the option is specified once,
              only run a single scrubbing thread at a time.  If given
              more than once, an artificial delay of 100us is added to
              each scrub call to reduce CPU overhead even further.

       -C fd  This option causes xfs_scrub to write progress information
              to the specified file description so that the progress of
              the filesystem check can be monitored.  If the file
              description is a tty, a fancy progress bar is rendered.
              Otherwise, a simple numeric status dump compatible with
              the fsck -C format is output.

       -e     Specifies what happens when errors are detected.  If
              shutdown is given, the filesystem will be taken offline if
              errors are found.  If continue is given, no action is
              taken if errors are found; this is the default behavior.

       -k     Do not call TRIM on the free space.

       -m file
              Search this file for mounted filesystems instead of
              /etc/mtab.

       -n     Only check filesystem metadata.  Do not repair or optimize
              anything.

       -T     Print timing and memory usage information for each phase.

       -v     Enable verbose mode, which prints periodic status updates.

       -V     Prints the version number and exits.

       -x     Read all file data extents to look for disk errors.
              xfs_scrub will issue O_DIRECT reads to the block device
              directly.  If the block device is a SCSI disk, it will
              instead issue READ VERIFY commands directly to the disk.
              If media errors are found, the error report will include
              the disk offset, in bytes.  If the media errors affect a
              file, the report will also include the inode number and
              file offset, in bytes.  These actions will confirm that
              all file data blocks can be read from storage.

OPTIMIZATIONS         top

       Optimizations supported by this program include, but are not
       limited to:

       • Instructing the underlying storage to discard unused extents
         via the TRIM ioctl.

       • Updating secondary superblocks to match the primary superblock.

       • Turning off shared block write checks for files that no longer
         share blocks.

REPAIRS         top

       Repairs are performed by calling into the kernel.  This limits
       the scope of repair activities to rebuilding primary data
       structures from secondary data structures, or secondary
       structures from primary structures.  The existence of secondary
       data structures may require features that can only be turned on
       from mkfs.xfs(8).  If errors cannot be repaired, the filesystem
       must be unmounted and xfs_repair(8) run.  Repairs supported by
       the kernel include, but are not limited to:

       • Reconstructing extent allocation data.

       • Rebuilding free space information.

       • Rebuilding inode indexes.

       • Fixing minor corruptions of inode records.

       • Recalculating reference count information.

       • Reconstructing reverse mapping data from primary extent
         allocation data.

       • Scheduling a quotacheck for the next mount.

       If corrupt metadata is successfully repaired, this program will
       log that a repair has succeeded instead of a corruption report.

EXIT CODE         top

       The exit code returned by xfs_scrub is the sum of the following
       conditions:
            0    - No errors
            1    - File system errors left uncorrected
            2    - File system optimizations possible
            4    - Operational error
            8    - Usage or syntax error

CAVEATS         top

       xfs_scrub is an immature utility!  Do not run this program unless
       you have backups of your data!  This program takes advantage of
       in-kernel scrubbing to verify a given data structure with locks
       held and can keep the filesystem busy for a long time.  The
       kernel must be new enough to support the SCRUB_METADATA ioctl.

       If errors are found and cannot be repaired, the filesystem must
       be unmounted and repaired.

SEE ALSO         top

       xfs_repair(8).

COLOPHON         top

       This page is part of the xfsprogs (utilities for XFS filesystems)
       project.  Information about the project can be found at 
       ⟨http://xfs.org/⟩.  If you have a bug report for this manual page,
       send it to linux-xfs@vger.kernel.org.  This page was obtained
       from the project's upstream Git repository
       ⟨https://git.kernel.org/pub/scm/fs/xfs/xfsprogs-dev.git⟩ on
       2021-06-20.  (At that time, the date of the most recent commit
       that was found in the repository was 2021-05-21.)  If you
       discover any rendering problems in this HTML version of the page,
       or you believe there is a better or more up-to-date source for
       the page, or you have corrections or improvements to the
       information in this COLOPHON (which is not part of the original
       manual page), send a mail to man-pages@man7.org

                                                            xfs_scrub(8)

Pages that refer to this page: ioctl_xfs_scrub_metadata(2)xfs_scrub_all(8)