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

6       xfs_admin - change parameters of an XFS filesystem
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SYNOPSIS

9       xfs_admin  [  -eflpu  ]  [  -c  0|1 ] [ -L label ] [ -U uuid ] device [
10       logdev ]
11       xfs_admin -V
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DESCRIPTION

14       xfs_admin uses the xfs_db(8) command to modify various parameters of  a
15       filesystem.
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17       Devices  that  are  mounted  cannot  be  modified.  Administrators must
18       unmount filesystems before xfs_admin or xfs_db(8) can  convert  parame‐
19       ters.   A  number of parameters of a mounted filesystem can be examined
20       and modified using the xfs_growfs(8) command.
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22       The optional logdev parameter specifies the device special  file  where
23       the  filesystem's  external  log  resides.   This  is required only for
24       filesystems that use an external log.  See the mkfs.xfs -l option,  and
25       refer to xfs(5) for a detailed description of the XFS log.
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OPTIONS

28       -e     Enables  unwritten  extent support on a filesystem that does not
29              already have this enabled (for legacy filesystems, it  can't  be
30              disabled anymore at mkfs time).
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32       -f     Specifies that the filesystem image to be processed is stored in
33              a regular file at device (see the mkfs.xfs -d file option).
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35       -j     Enables version 2 log format (journal format  supporting  larger
36              log buffers).
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38       -l     Print the current filesystem label.
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40       -p     Enable 32bit project identifier support (PROJID32BIT feature).
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42       -u     Print  the  current  filesystem UUID (Universally Unique IDenti‐
43              fier).
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45       -c 0|1 Enable (1) or disable (0) lazy-counters in the filesystem.
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47              Lazy-counters may  not  be  disabled  on  Version  5  superblock
48              filesystems (i.e. those with metadata CRCs enabled).
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50              This operation may take quite a bit of time on large filesystems
51              as the entire filesystem needs to be scanned when this option is
52              changed.
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54              With  lazy-counters  enabled,  the superblock is not modified or
55              logged on every change of the  free-space  and  inode  counters.
56              Instead,  enough  information  is  kept  in  other  parts of the
57              filesystem to be able to maintain  the  counter  values  without
58              needing  to  keep them in the superblock. This gives significant
59              improvements in performance on some configurations and  metadata
60              intensive workloads.
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62       -L label
63              Set the filesystem label to label.  XFS filesystem labels can be
64              at most 12 characters long; if label is longer than  12  charac‐
65              ters,  xfs_admin  will  truncate it and print a warning message.
66              The filesystem label can be cleared using the special "--" value
67              for label.
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69       -U uuid
70              Set  the  UUID  of  the filesystem to uuid.  A sample UUID looks
71              like this: "c1b9d5a2-f162-11cf-9ece-0020afc76f16".  The uuid may
72              also  be  nil,  which  will  set the filesystem UUID to the null
73              UUID.  The uuid may also be generate, which will generate a  new
74              UUID  for the filesystem.  Note that on CRC-enabled filesystems,
75              this will set an incompatible flag such that older kernels  will
76              not  be able to mount the filesystem.  To remove this incompati‐
77              ble flag, use restore, which will restore the original UUID  and
78              remove the incompatible feature flag as needed.
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80       -V     Prints the version number and exits.
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82       The mount(8) manual entry describes how to mount a filesystem using its
83       label or UUID, rather than its block special device name.
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SEE ALSO

86       mkfs.xfs(8), mount(8), xfs_db(8), xfs_growfs(8), xfs_repair(8), xfs(5).
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