From Linux Man Pages
xfs_freeze - suspend access to an XFS filesystem
xfs_freeze [ -fu ] mount-point
DESCRIPTION
xfs_freeze suspends and resumes access to an XFS filesystem (see xfs(5)).
xfs_freeze halts new access to the filesystem and creates a stable image on disk. xfs_freeze is intended to be
used with volume managers and hardware RAID devices that support the creation of snapshots.
The mount-point argument is the pathname of the directory where the filesystem is mounted. The filesystem must
be mounted to be frozen (see mount(8)).
The -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.
Note that even after freezing, the on-disk filesystem can contain information on files that are still in the pro-
cess of unlinking. These files will not be unlinked until the filesystem is unfrozen or a clean mount of the
snapshot is complete.
The -u 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.
One of -f or -u must be supplied to xfs_freeze.
NOTES
A copy of a frozen XFS filesystem will usually have the same universally unique identifier (UUID) as the origi-
nal, and thus may be prevented from being mounted. The XFS nouuid mount option can be used to circumvent this
issue.
RELATED
xfs(5), lvm(8), mount(8).
CATEGORY