FSFREEZE(8)		     System Administration		   FSFREEZE(8)

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 filesystem to be frozen from new
	   modifications. When this is selected, all ongoing transactions in
	   the filesystem are allowed to complete, new write(2) 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.

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

       -V, --version
	   Display version 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.

NOTES
       This man page is based on xfs_freeze(8).

AUTHORS
       Written by Hajime Taira.

SEE ALSO
       mount(8)

REPORTING BUGS
       For bug reports, use the issue tracker
       <https://github.com/util-linux/util-linux/issues>.

AVAILABILITY
       The fsfreeze command is part of the util-linux package which can be
       downloaded from Linux Kernel Archive
       <https://www.kernel.org/pub/linux/utils/util-linux/>.

util-linux 2.41.2		  2025-09-22			   FSFREEZE(8)