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c372860d | 1 | .TH FSFREEZE 8 "July 2014" "util-linux" "System Administration" |
f0bef3ca | 2 | .SH NAME |
c372860d | 3 | fsfreeze \- suspend access to a filesystem (Ext3/4, ReiserFS, JFS, XFS) |
f0bef3ca | 4 | .SH SYNOPSIS |
7de20424 KZ |
5 | .B fsfreeze |
6 | .BR \--freeze | \--unfreeze | |
7 | .IR mountpoint | |
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8 | |
9 | .SH DESCRIPTION | |
10 | .B fsfreeze | |
c372860d | 11 | suspends or resumes access to a filesystem. |
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12 | .PP |
13 | .B fsfreeze | |
c372860d | 14 | halts any new access to the filesystem and creates a stable image on disk. |
f0bef3ca | 15 | .B fsfreeze |
c372860d | 16 | is intended to be used with hardware RAID devices that support the creation |
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17 | of snapshots. |
18 | .PP | |
19 | .B fsfreeze | |
5e511de1 | 20 | is unnecessary for |
f0bef3ca | 21 | .B device-mapper |
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22 | devices. The device-mapper (and LVM) automatically freezes a filesystem |
23 | on the device when a snapshot creation is requested. | |
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24 | For more details see the |
25 | .BR dmsetup (8) | |
26 | man page. | |
27 | .PP | |
28 | The | |
c372860d | 29 | .I mountpoint |
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30 | argument is the pathname of the directory where the filesystem |
31 | is mounted. | |
32 | The filesystem must be mounted to be frozen (see | |
33 | .BR mount (8)). | |
e442ab76 | 34 | .PP |
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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 | |
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37 | .BR mount (8)). |
38 | ||
f0bef3ca | 39 | .SH OPTIONS |
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40 | .TP |
41 | .BR \-f , " \-\-freeze" | |
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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. | |
c372860d | 48 | .sp |
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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. | |
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53 | .TP |
54 | .BR \-u , " \-\-unfreeze" | |
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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. | |
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58 | .TP |
59 | .BR \-V , " \-\-version" | |
b4362b6f | 60 | Display version information and exit. |
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61 | .TP |
62 | .BR \-h , " \-\-help" | |
63 | Display help text and exit. | |
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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) | |
67 | .BR btrfs , | |
68 | .BR ext2/3/4 , | |
69 | .BR f2fs , | |
70 | .BR jfs , | |
71 | .BR nilfs2 , | |
72 | .BR reiserfs , | |
73 | and | |
74 | .BR xfs . | |
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. | |
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78 | .SH AUTHOR |
79 | .PP | |
80 | Written by Hajime Taira. | |
81 | .SH NOTES | |
82 | .PP | |
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83 | This man page is based on |
84 | .BR xfs_freeze (8). | |
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85 | .SH SEE ALSO |
86 | .BR mount (8) | |
87 | .SH AVAILABILITY | |
601d12fb | 88 | The fsfreeze command is part of the util-linux package and is available from |
d673b74e | 89 | https://www.kernel.org/pub/linux/utils/util-linux/. |