fsfreeze(8)

1FSFREEZE(8)                  System Administration                 FSFREEZE(8)
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NAME

6       fsfreeze - suspend access to a filesystem (Ext3/4, ReiserFS, JFS, XFS)
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SYNOPSIS

9       fsfreeze --freeze|--unfreeze mountpoint
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DESCRIPTION

13       fsfreeze suspends or resumes access to a filesystem.
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15       fsfreeze  halts  any  new access to the filesystem and creates a stable
16       image on disk.  fsfreeze is intended to  be  used  with  hardware  RAID
17       devices that support the creation of snapshots.
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19       fsfreeze  is  unnecessary for device-mapper devices.  The device-mapper
20       (and LVM) automatically freezes a filesystem on the device when a snap‐
21       shot  creation  is  requested.  For more details see the dmsetup(8) man
22       page.
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24       The mountpoint argument is the pathname  of  the  directory  where  the
25       filesystem  is  mounted.   The  filesystem must be mounted to be frozen
26       (see mount(8)).
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28       Note that access-time updates are also suspended if the  filesystem  is
29       mounted  with the traditional atime behavior (mount option strictatime,
30       for more details see mount(8)).
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OPTIONS

34       -f, --freeze
35              This option requests the specified a  filesystem  to  be  frozen
36              from  new  modifications.   When  this  is selected, all ongoing
37              transactions in the filesystem  are  allowed  to  complete,  new
38              write  system  calls  are  halted,  other calls which modify the
39              filesystem are halted, and all dirty  data,  metadata,  and  log
40              information  are  written  to  disk.   Any process attempting to
41              write to the  frozen  filesystem  will  block  waiting  for  the
42              filesystem to be unfrozen.
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44              Note  that  even after freezing, the on-disk filesystem can con‐
45              tain information on files that  are  still  in  the  process  of
46              unlinking.   These files will not be unlinked until the filesys‐
47              tem is unfrozen or a clean mount of the snapshot is complete.
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49       -u, --unfreeze
50              This option is used to un-freeze the filesystem and allow opera‐
51              tions  to  continue.   Any  filesystem  modifications  that were
52              blocked by the freeze are unblocked and allowed to complete.
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54       -V, --version
55              Display version information and exit.
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57       -h, --help
58              Display help text and exit.
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FILESYSTEM SUPPORT

61       This command will work only if  filesystem  supports  has  support  for
62       freezing.   List  of  these  filesystems  include  (2016-12-18)  btrfs,
63       ext2/3/4, f2fs, jfs, nilfs2, reiserfs, and xfs.  Previous list  may  be
64       incomplete,  as  more filesystems get support.  If in doubt easiest way
65       to know if a filesystem has support is create a  small  loopback  mount
66       and test freezing it.
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NOTES

69       This man page is based on xfs_freeze(8).
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AUTHORS

72       Written by Hajime Taira.
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AVAILABILITY

78       The fsfreeze command is part of the util-linux package and is available
79       from https://www.kernel.org/pub/linux/utils/util-linux/.
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83util-linux                         July 2014                       FSFREEZE(8)