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XFS is a 64-bit journaling file system initially developed by Silicon Graphics. It is designed for parallel I/O based on allocation groups. This allows a system to scale based on the number of I/O threads and file system bandwidth. It is designed to span multiple storage devices. XFS includes its own volume manager.It uses B+ trees for the directories and file allocation. The file system is partitioned into allocation groups (AG) that have their own allocation and free space management. Files are allocated used extents (Fig. 2) that use contiguous blocks when possible. The number of extents usually grows as a file’s size increases. XFS can handle variable block sizes, sparse files, and snapshots.