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.

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 at https://github.com/karelzak/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/>.