xfs_fsr

What xfs_fsr is

xfs_fsr is a free Linux utility in the xfsprogs project for reorganizing mounted XFS filesystems, improving file extent layout one file at a time. With no arguments, it chooses files with the highest extent counts and tries to defragment the top 10% during each pass. A standard run can continue for up to two hours; it records its stopping point so a later run can resume. You can target named filesystems or individual files, with one pass through each target.

The utility makes a copy of a file in a temporary location, then atomically switches the data extents of the original and copy. It needs enough free disk space to copy each target, and that space must be less fragmented than the original file. On systems with quotas, the file owner also needs enough remaining file-space quota. xfs_fsr skips files currently mapped in memory, files marked no-defrag, and filesystem entries that are not mounted read-write. The no-defrag flag can be changed with the chattr command in xfs_io. The manual says system partitions generally do not need this utility and warns that moving bootloader files can prevent a system from booting unless lilo is rerun before reboot. Bug reports are directed to the linux-xfs mailing list.

Who it suits

xfs_fsr suits Linux users who need to reorganize files on mounted XFS filesystems, either by letting it select files or by specifying targets. It is intended for systems where targets can be mounted read-write and there is enough less-fragmented free space and, when quotas apply, owner quota for file copies.

Limits

The free plan applies only to XFS filesystems. Processing requires enough free disk space to copy a target file, and quota-enabled systems also require sufficient remaining file-space quota for its owner; mapped files and targets not mounted read-write are skipped.

Getting started

1. Open the xfs.org project website.
2. Use a Linux system with an XFS filesystem mounted read-write.
3. Ensure enough less-fragmented free disk space is available to copy the target file.
4. If quotas are enabled, ensure the file owner has enough remaining file-space quota.
5. Run xfs_fsr without arguments for automatic selection, or specify filesystems or individual files.

Verdict

Choose xfs_fsr if you need a free Linux utility to reorganize mounted XFS filesystems and can meet its disk-space and mount requirements. Look elsewhere if you need a tool for filesystems other than XFS or need it to process files mapped in memory.