xfs_scrub(8)

1xfs_scrub(8)                System Manager's Manual               xfs_scrub(8)
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NAME

6       xfs_scrub - check the contents of a mounted XFS filesystem
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SYNOPSIS

9       xfs_scrub [ -abCemnTvx ] mount-point
10       xfs_scrub -V
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DESCRIPTION

13       xfs_scrub  attempts  to  check and repair all metadata in a mounted XFS
14       filesystem.
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16       WARNING!  This program is EXPERIMENTAL, which means that  its  behavior
17       and interface could change at any time!
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19       xfs_scrub asks the kernel to scrub all metadata objects in the filesys‐
20       tem.  Metadata records are scanned for obviously bad  values  and  then
21       cross-referenced  against  other  metadata.  The goal is to establish a
22       reasonable confidence about the consistency of the  overall  filesystem
23       by examining the consistency of individual metadata records against the
24       other metadata in the filesystem.  Damaged metadata can be rebuilt from
25       other  metadata  if  there  exists  redundant data structures which are
26       intact.
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28       Filesystem corruption and optimization opportunities will be logged  to
29       the  standard  error  stream.   Enabling verbose mode will increase the
30       amount of status information sent to the output.
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32       If the kernel scrub reports that metadata needs  repairs  or  optimiza‐
33       tions  and  the user does not pass -n on the command line, this program
34       will ask the kernel to make the repairs and to  perform  the  optimiza‐
35       tions.   See the sections about optimizations and repairs for a list of
36       optimizations and repairs known to this program.  The  kernel  may  not
37       support  repairing  or optimizing the filesystem.  If this is the case,
38       the filesystem must be unmounted and xfs_repair(8) run on the  filesys‐
39       tem to fix the problems.
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OPTIONS

42       -a errors
43              Abort if more than this many errors are found on the filesystem.
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45       -b     Run  in  background mode.  If the option is specified once, only
46              run a single scrubbing thread at a time.   If  given  more  than
47              once,  an  artificial delay of 100us is added to each scrub call
48              to reduce CPU overhead even further.
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50       -C fd  This option causes xfs_scrub to write  progress  information  to
51              the  specified  file  description  so  that  the progress of the
52              filesystem check can be monitored.  If the file description is a
53              tty,  a  fancy  progress  bar  is rendered.  Otherwise, a simple
54              numeric status dump compatible with the fsck -C format  is  out‐
55              put.
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57       -e     Specifies what happens when errors are detected.  If shutdown is
58              given, the filesystem will be taken offline if errors are found.
59              If  continue  is  given, no action is taken if errors are found;
60              this is the default behavior.
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62       -k     Do not call TRIM on the free space.
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64       -m file
65              Search this file for mounted filesystems instead of /etc/mtab.
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67       -n     Only check filesystem metadata.  Do not repair or optimize  any‐
68              thing.
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70       -T     Print timing and memory usage information for each phase.
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72       -v     Enable verbose mode, which prints periodic status updates.
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74       -V     Prints the version number and exits.
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76       -x     Read  all  file data extents to look for disk errors.  xfs_scrub
77              will issue O_DIRECT reads to the block device directly.  If  the
78              block  device  is a SCSI disk, it will instead issue READ VERIFY
79              commands directly to the disk.  These actions will confirm  that
80              all file data blocks can be read from storage.
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OPTIMIZATIONS

83       Optimizations  supported  by  this program include, but are not limited
84       to:
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86       · Instructing the underlying storage to discard unused extents via  the
87         TRIM ioctl.
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REPAIRS

90       This  program  currently  does not support making any repairs.  Corrup‐
91       tions can only be  fixed  by  unmounting  the  filesystem  and  running
92       xfs_repair(8).
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EXIT CODE

95       The  exit code returned by xfs_scrub is the sum of the following condi‐
96       tions:
97            0    - No errors
98            1    - File system errors left uncorrected
99            2    - File system optimizations possible
100            4    - Operational error
101            8    - Usage or syntax error
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CAVEATS

104       xfs_scrub is an immature utility!  Do not run this program  unless  you
105       have  backups  of your data!  This program takes advantage of in-kernel
106       scrubbing to verify a given data structure with locks held and can keep
107       the  filesystem busy for a long time.  The kernel must be new enough to
108       support the SCRUB_METADATA ioctl.
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110       If errors are found and cannot be  repaired,  the  filesystem  must  be
111       unmounted and repaired.
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