xfs_freeze

xfs_freeze [-f | -u] mount-point

-f
    Freezes the specified XFS filesystem, suspending all I/O operations to it. This creates a consistent state for backup or snapshot purposes.

-u
    Unfreezes the specified XFS filesystem, resuming all I/O operations that were previously suspended.

xfs_freeze is a command-line utility used to suspend or resume I/O operations on an XFS filesystem. Its primary purpose is to create a consistent on-disk image of the filesystem for reliable backup or snapshot operations. When an XFS filesystem is frozen using this command, all data access and modification activities are temporarily halted, ensuring data integrity during the backup process. This prevents inconsistencies that could arise from changes occurring while the backup is being made. After the backup or snapshot is complete, the filesystem can be unfrozen, allowing normal operations to resume. The command operates directly on a specified XFS mount point and typically requires root privileges.

Using xfs_freeze will halt all I/O on the target filesystem, potentially causing applications or services accessing it to hang indefinitely until the filesystem is unfrozen.
It should never be used on filesystems mounted read-only.
The command must be executed with superuser (root) privileges.
It is critical to unfreeze the filesystem (using -u) after completing backup or snapshot operations; leaving it frozen will render the filesystem unusable.

xfs_freeze is primarily utilized to achieve a consistent state of an XFS filesystem before performing a snapshot or backup. This ensures data integrity by preventing any changes or writes to the filesystem during the backup process.

Typically, an administrator would first freeze the filesystem (xfs_freeze -f /mount/point), then perform a volume snapshot or initiate a backup process (e.g., LVM snapshot, rsync), and finally unfreeze the filesystem (xfs_freeze -u /mount/point).

The command requires superuser (root) privileges to execute successfully, as it directly manipulates low-level filesystem states and global I/O operations for a mounted filesystem.

xfs_freeze is an integral part of the XFS filesystem utilities. XFS was originally developed by Silicon Graphics (SGI) for its IRIX operating system in the early 1990s, renowned for its high performance and scalability. It was later ported to Linux and has been included in the mainline kernel since 2002. The xfs_freeze utility specifically leverages XFS's robust journaling and structural properties to provide a reliable method for creating consistent filesystem snapshots, a crucial feature for enterprise-level data management and backup strategies. Its continued usage highlights XFS's relevance in modern Linux server environments, particularly for scenarios requiring crash-consistent backups of large datasets.

fsfreeze(8), mount(8), xfs(5), xfs_io(8)