xfs_freeze

xfs_freeze [-f] mount_point
xfs_freeze -u mount_point

-f
    Force freeze even if the filesystem is already frozen. Use with caution; can cause inconsistencies if another process is already relying on the frozen state.

-u
    Unfreeze the filesystem at the specified mount_point.

mount_point
    The mount point of the XFS filesystem to be frozen or unfrozen.

The xfs_freeze command suspends all I/O operations on an XFS filesystem. This allows you to take a consistent snapshot of the filesystem, typically for backup purposes. Freezing prevents any further modifications to the filesystem, ensuring data consistency during the backup process.

Once the snapshot is complete, xfs_freeze is used again to thaw the filesystem, resuming normal I/O operations. It achieves this by signaling the filesystem's journal to a consistent state. This command is crucial for systems that require consistent backups without downtime, as it minimizes the impact on running applications. Proper use ensures minimal data loss or corruption during backup and restore procedures. The operation requires superuser privileges.

Failing to unfreeze a filesystem after freezing it can lead to severe performance degradation or filesystem corruption. Always ensure to unfreeze after the snapshot is complete. Incorrect mount path leads to undefined operation.

xfs_freeze will return an error if the specified mount point does not exist, if the filesystem is not an XFS filesystem, or if the user does not have sufficient privileges. It also errors if freezing fails, such as in situations where the filesystem is already being frozen by another process.

Freezing the filesystem mounted at /data:
xfs_freeze /data

Taking a snapshot using LVM:
lvcreate -L 1G -s -n data_snap /dev/vg/data

Unfreezing the filesystem:
xfs_freeze -u /data

The xfs_freeze command was developed as part of the XFS filesystem utilities to provide a method for creating consistent snapshots. It has been a standard tool for XFS filesystem administration since its inclusion in the xfsprogs package. Its design is deeply integrated with the XFS journal, relying on it to ensure data consistency during the freeze/unfreeze operations.

xfs(5), mount(8), umount(8)