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FSFREEZE(8)                  System Administration                 FSFREEZE(8)

NAME
       fsfreeze - suspend access to a filesystem (Linux Ext3/4, ReiserFS, JFS,
       XFS)
SYNOPSIS
       fsfreeze --freeze|--unfreeze mountpoint

DESCRIPTION
       fsfreeze suspends and resumes access to an filesystem
       fsfreeze halts new access to the filesystem and creates a stable  image
       on  disk.   fsfreeze  is intended to be used with hardware RAID devices
       that support the creation of snapshots.
       fsfreeze is unnecessary for device-mapper  devices.  The  device-mapper
       (and  LVM)  automatically freezes filesystem on the device when a snap-
       shot creation is requested.  For more details see  the  dmsetup(8)  man
       page.
       The  mount-point  argument  is  the pathname of the directory where the
       filesystem is mounted.  The filesystem must be  mounted  to  be  frozen
       (see mount(8)).
       Note  that  access  time updates are also suspends if the filesystem is
       mounted with the traditional atime semantics (mount option strictatime,
       for more details see mount(8)).

OPTIONS
       -h, --help
              Print help and exit.
       -f, --freeze
              This  option  requests  the  specified a filesystem to be frozen
              from new modifications.  When  this  is  selected,  all  ongoing
              transactions  in  the  filesystem  are  allowed to complete, new
              write system calls are halted,  other  calls  which  modify  the
              filesystem  are  halted,  and  all dirty data, metadata, and log
              information are written to  disk.   Any  process  attempting  to
              write  to  the  frozen  filesystem  will  block  waiting for the
              filesystem to be unfrozen.
              Note that even after freezing, the on-disk filesystem  can  con-
              tain  information  on  files  that  are  still in the process of
              unlinking.  These files will not be unlinked until the  filesys-
              tem is unfrozen or a clean mount of the snapshot is complete.
       -u, --unfreeze
              This option is used to un-freeze the filesystem and allow opera-
              tions to  continue.   Any  filesystem  modifications  that  were
              blocked by the freeze are unblocked and allowed to complete.
       -V, --version
              Show version number and exit.
AUTHOR
       Written by Hajime Taira.
NOTES
       This man page based on xfs_freeze.  One of -f or -u must be supplied to
       fsfreeze.
SEE ALSO
       mount(8)
AVAILABILITY
       The fsfreeze command is part of the util-linux package and is available
       from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.


util-linux                         May 2010                        FSFREEZE(8)