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  ] [ -O featurelist ] [ -c 0|1 ] [ -L label ] [ -U
10       uuid ] [ -r rtdev ] device [ 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.
16
17       Devices  that  are mounted cannot be modified.  Administrators must un‐
18       mount filesystems before xfs_admin or xfs_db(8) can convert parameters.
19       A number of parameters of a mounted filesystem can be examined and mod‐
20       ified using the xfs_growfs(8) command.
21
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).
31
32              This option only applies to the deprecated V4 format.
33
34       -f     Specifies that the filesystem image to be processed is stored in
35              a regular file at device (see the mkfs.xfs -d file option).
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37       -j     Enables version 2 log format (journal format  supporting  larger
38              log buffers).
39
40              This option only applies to the deprecated V4 format.
41
42       -l     Print the current filesystem label.
43
44       -p     Enable 32bit project identifier support (PROJID32BIT feature).
45
46              This option only applies to the deprecated V4 format.
47
48       -u     Print  the  current  filesystem UUID (Universally Unique IDenti‐
49              fier).
50
51       -c 0|1 Enable (1) or disable (0) lazy-counters in the filesystem.
52
53              Lazy-counters may  not  be  disabled  on  Version  5  superblock
54              filesystems (i.e. those with metadata CRCs enabled).
55
56              In  other  words,  this option only applies to the deprecated V4
57              format.
58
59              This operation may take quite a bit of time on large filesystems
60              as the entire filesystem needs to be scanned when this option is
61              changed.
62
63              With lazy-counters enabled, the superblock is  not  modified  or
64              logged on every change of the free-space and inode counters. In‐
65              stead, enough information is kept in other parts of the filesys‐
66              tem to be able to maintain the counter values without needing to
67              keep them in the superblock. This gives significant improvements
68              in  performance  on  some  configurations and metadata intensive
69              workloads.
70
71       -L label
72              Set the filesystem label to label.  XFS filesystem labels can be
73              at  most  12 characters long; if label is longer than 12 charac‐
74              ters, xfs_admin will truncate it and print  a  warning  message.
75              The filesystem label can be cleared using the special "--" value
76              for label.
77
78       -O feature1=status,feature2=status...
79              Add or remove features on an existing V5 filesystem.   The  fea‐
80              tures  should  be  specified  as a comma-separated list.  status
81              should be either 0 to disable the feature or  1  to  enable  the
82              feature.  Note, however, that most features cannot be disabled.
83
84              NOTE: Administrators must ensure the filesystem is clean by run‐
85              ning xfs_repair -n to inspect the filesystem  before  performing
86              the  upgrade.  If corruption is found, recovery procedures (e.g.
87              reformat followed by restoration from backup; or running xfs_re‐
88              pair without the -n) must be followed to clean the filesystem.
89
90              Supported features are as follows:
91
92              inobtcount
93                  Keep a count the number of blocks in each inode btree in the
94                  AGI.  This reduces mount time by speeding up metadata  space
95                  reservation  calculations.   The  filesystem cannot be down‐
96                  graded after this feature is  enabled.   Once  enabled,  the
97                  filesystem will not be writable by older kernels.  This fea‐
98                  ture was added to Linux 5.10.
99
100              bigtime
101                  Upgrade a filesystem to support larger timestamps up to  the
102                  year  2486.   The filesystem cannot be downgraded after this
103                  feature is enabled.  Once enabled, the filesystem  will  not
104                  be  mountable  by  older kernels.  This feature was added to
105                  Linux 5.10.
106
107       -U uuid
108              Set the UUID of the filesystem to uuid.   A  sample  UUID  looks
109              like this: "c1b9d5a2-f162-11cf-9ece-0020afc76f16".  The uuid may
110              also be nil, which will set the  filesystem  UUID  to  the  null
111              UUID.   The uuid may also be generate, which will generate a new
112              UUID for the filesystem.  Note that on CRC-enabled  filesystems,
113              this  will set an incompatible flag such that older kernels will
114              not be able to mount the filesystem.  To remove this  incompati‐
115              ble  flag, use restore, which will restore the original UUID and
116              remove the incompatible feature flag as needed.
117
118       -r rtdev
119              Specifies the device special file where the  filesystem's  real‐
120              time  section  resides.   Only for those filesystems which use a
121              realtime section.
122
123       -V     Prints the version number and exits.
124
125       The mount(8) manual entry describes how to mount a filesystem using its
126       label or UUID, rather than its block special device name.
127

SEE ALSO

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