Purpose: xfs_fsr reorganizes mounted XFS filesystems by improving the layout of file extents one file at a time.
Selection: With no arguments, it selects files with the largest numbers of extents and attempts to defragment the top 10% on each pass.
Time limit: The default run lasts up to two hours and records where it stopped so it can resume later.
Targeting: It can be run on named filesystems or individual files, making one pass through each specified target.
How it works: It copies a file to a temporary location and atomically interchanges the data extents of the original and temporary files.
Disk space requirement: Reorganization requires enough free disk space to copy the target file, with space less fragmented than the original file.
Quota requirement: On systems using quotas, the file owner must have enough remaining file space quota for the copy.
Mapped files: It does not operate on files that are currently mapped in memory.
No-defrag flag: Files marked no-defrag are skipped, and the flag can be set or cleared with xfs_io's chattr command.
Access requirement: The filesystem must be mounted read-write; entries without the rw option are skipped.
Operational caution: The manual says system partitions generally do not need xfs_fsr and cautions that moving bootloader files can make a system unbootable unless lilo is rerun before reboot.
Project and support: The manual identifies xfs_fsr as part of the xfsprogs project and directs bug reports to the linux-xfs mailing list.
Price from: Free

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Best Disk Defragmentation Software in 2026#11 of 22

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Sources

man7.org/linux/man-pages/man8/xfs_fsr.8.html· checked 4 Oct 2026