NAME

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

SYNOPSIS

       fsfreeze --freeze|--unfreeze mountpoint

DESCRIPTION

       fsfreeze suspends or resumes access to a filesystem.

       fsfreeze halts any 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 a
       filesystem on the device when a snapshot creation is requested.  For more details see the dmsetup(8)  man
       page.

       The mountpoint 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 suspended if the filesystem is mounted with the traditional atime
       behavior (mount option strictatime, for more details see mount(8)).

OPTIONS

       -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 contain information on files that are
              still in the process of unlinking.  These files will not  be  unlinked  until  the  filesystem  is
              unfrozen or a clean mount of the snapshot is complete.

       -u, --unfreeze
              This  option is used to un-freeze the filesystem and allow operations to continue.  Any filesystem
              modifications that were blocked by the freeze are unblocked and allowed to complete.

       -V, --version
              Display version information and exit.

       -h, --help
              Display help text and exit.

FILESYSTEM SUPPORT

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

AUTHOR

       Written by Hajime Taira.

NOTES

       This man page is based on xfs_freeze(8).

SEE ALSO

       mount(8)

AVAILABILITY

       The   fsfreeze   command   is   part   of   the   util-linux    package    and    is    available    from
       https://www.kernel.org/pub/linux/utils/util-linux/.

util-linux                                          July 2014                                        FSFREEZE(8)