| .TH xfs_freeze 8 |
| .SH NAME |
| xfs_freeze \- suspend access to an XFS filesystem |
| .SH SYNOPSIS |
| .B xfs_freeze |
| [ |
| .B \-f |
| | |
| .B \-u |
| ] |
| .I mount-point |
| .br |
| .B xfs_freeze \-V |
| .fi |
| .SH DESCRIPTION |
| .B xfs_freeze |
| suspends and resumes access to an XFS filesystem (see |
| .BR xfs (5)). |
| .PP |
| .B xfs_freeze |
| halts new access to the filesystem and creates a stable image on disk. |
| .B xfs_freeze |
| is intended to be used with volume managers and hardware RAID devices |
| that support the creation of snapshots. |
| .PP |
| The |
| .I mount-point |
| argument is the pathname of the directory where the filesystem |
| is mounted. |
| The filesystem must be mounted to be frozen (see |
| .BR mount (8)). |
| .PP |
| .PP |
| The |
| .B \-f |
| flag requests the specified XFS 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. |
| .PP |
| 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. |
| .PP |
| The |
| .B \-u |
| flag 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. |
| .PP |
| The |
| .B \-V |
| flag prints the version number and exits. |
| .PP |
| Unless |
| .B \-V |
| is specified, one of |
| .B \-f |
| or |
| .B \-u |
| must be supplied to |
| .BR xfs_freeze . |
| .SH NOTES |
| A copy of a frozen XFS filesystem will usually have the same universally |
| unique identifier (UUID) as the original, and thus may be prevented from |
| being mounted. |
| The XFS |
| .B nouuid |
| mount option can be used to circumvent this issue. |
| .PP |
| In Linux kernel version 2.6.29, the interface which XFS uses to freeze |
| and unfreeze was elevated to the VFS, so that this tool can now be |
| used on many other Linux filesystems. |
| .SH SEE ALSO |
| .BR xfs (5), |
| .BR lvm (8), |
| .BR mount (8). |
