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       xfs_admin -V
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DESCRIPTION

13       xfs_admin  uses the xfs_db(8) command to modify various parameters of a
14       filesystem.
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16       Devices that are  mounted  cannot  be  modified.   Administrators  must
17       unmount  filesystems  before xfs_admin or xfs_db(8) can convert parame‐
18       ters.  A number of parameters of a mounted filesystem can  be  examined
19       and modified using the xfs_growfs(8) command.
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OPTIONS

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

80       mkfs.xfs(8), mount(8), xfs_db(8), xfs_growfs(8), xfs_repair(8), xfs(5).
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84                                                                  xfs_admin(8)
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