xfs_scrub - check and repair the contents of a mounted XFS filesystem
xfs_scrub [
-abCemnTvx ]
mount-point
xfs_scrub -V
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.
-
-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 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 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.
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
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.
xfs_repair(8).