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
Print 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 at
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 2.38.1 2022-05-11 FSFREEZE(8)
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