1 .TH FSFREEZE 8 "July 2014" "util-linux" "System Administration"
3 fsfreeze \- suspend access to a filesystem (Ext3/4, ReiserFS, JFS, XFS)
6 .BR \--freeze | \--unfreeze
11 suspends or resumes access to a filesystem.
14 halts any new access to the filesystem and creates a stable image on disk.
16 is intended to be used with hardware RAID devices that support the creation
22 devices. The device-mapper (and LVM) automatically freezes a filesystem
23 on the device when a snapshot creation is requested.
24 For more details see the
30 argument is the pathname of the directory where the filesystem
32 The filesystem must be mounted to be frozen (see
35 Note that access-time updates are also suspended if the filesystem is mounted with
36 the traditional atime behavior (mount option \fBstrictatime\fR, for more details see
41 .BR \-f , " \-\-freeze"
42 This option requests the specified a filesystem to be frozen from new
43 modifications. When this is selected, all ongoing transactions in the
44 filesystem are allowed to complete, new write system calls are halted, other
45 calls which modify the filesystem are halted, and all dirty data, metadata, and
46 log information are written to disk. Any process attempting to write to the
47 frozen filesystem will block waiting for the filesystem to be unfrozen.
49 Note that even after freezing, the on-disk filesystem can contain
50 information on files that are still in the process of unlinking.
51 These files will not be unlinked until the filesystem is unfrozen
52 or a clean mount of the snapshot is complete.
54 .BR \-u , " \-\-unfreeze"
55 This option is used to un-freeze the filesystem and allow operations to
56 continue. Any filesystem modifications that were blocked by the freeze are
57 unblocked and allowed to complete.
59 .BR \-V , " \-\-version"
60 Display version information and exit.
63 Display help text and exit.
64 .SH FILESYSTEM SUPPORT
65 This command will work only if filesystem supports has support for freezing.
66 List of these filesystems include (2016-12-18)
75 Previous list may be incomplete, as more filesystems get support. If in
76 doubt easiest way to know if a filesystem has support is create a small
77 loopback mount and test freezing it.
80 Written by Hajime Taira.
83 This man page is based on
88 The fsfreeze command is part of the util-linux package and is available from
89 https://www.kernel.org/pub/linux/utils/util-linux/.