xfs_fsr

xfs_fsr [ options ] [ file ... ]

-v
    Enables verbose output, showing details of the defragmentation process.

-t max_time
    Specifies the maximum time (in minutes) for xfs_fsr to run. It will exit gracefully after this time.

-s
    Prints statistics about fragmentation and then exits without performing any defragmentation.

-m min_blocks
    Sets the minimum number of blocks an extent must be able to move to be considered for defragmentation.

-l min_len
    Specifies the minimum extent length (in blocks) to be considered for defragmentation.

-o offset
    Specifies the starting byte offset within a file to begin defragmentation. Used with file arguments.

-n length
    Specifies the length (in bytes) within a file to defragment, starting from the offset. Used with file arguments.

-p prog_report
    Sets the interval (in seconds) for printing progress reports during the defragmentation process.

-d
    Enables verbose debugging output, useful for developers or advanced troubleshooting.

-x
    Causes xfs_fsr to exit immediately upon encountering the first error.

-c
    Enables 'compact' mode, where xfs_fsr attempts to coalesce extents into larger, more contiguous ones.

-r
    Forces reallocation of all files, even if they are already reasonably contiguous. Can be useful for optimizing for specific block alignment.

file ...
    Specifies one or more files or directories to defragment. If omitted, the entire filesystem will be processed.

xfs_fsr (XFS filesystem reorganizer) is a utility designed to defragment mounted XFS filesystems. Its primary purpose is to improve I/O performance by reallocating file data blocks into contiguous regions on the disk. Over time, files can become fragmented, meaning their data is scattered across non-adjacent blocks, which increases disk seek times and degrades performance. xfs_fsr addresses this by reorganizing extents (contiguous blocks) for files and directories.

A key feature of xfs_fsr is its ability to operate online, allowing the filesystem to remain mounted and fully accessible during the defragmentation process. This minimizes downtime for critical systems. It can operate on an entire filesystem or be directed to defragment specific files or directories, offering flexibility based on performance needs. While XFS is inherently designed to minimize fragmentation, xfs_fsr provides a tool for specific workloads where fragmentation might still occur and impact performance, such as frequently modified large files or databases.

Running xfs_fsr can be I/O intensive and may temporarily impact system performance due to increased disk activity. While designed for online operation, sufficient free space is required as data blocks are reallocated. Defragmentation is not always necessary for XFS due to its design, and should be performed only when specific performance issues linked to fragmentation are observed. Avoid running on extremely busy filesystems without prior testing or during peak hours.

While the goal of xfs_fsr is to improve performance, the defragmentation process itself consumes significant system resources (CPU, memory, disk I/O). It is generally recommended to run xfs_fsr during off-peak hours or on systems that can tolerate temporary performance degradation. Monitoring system resources during execution is advisable.

A significant advantage of xfs_fsr is its ability to perform defragmentation on a live, mounted filesystem. This means that services utilizing the filesystem can continue to operate with minimal or no interruption, which is critical for high-availability environments. The utility handles concurrent filesystem activity gracefully.

xfs_fsr is part of the XFS filesystem utilities, known as xfsprogs. XFS itself was originally developed by Silicon Graphics (SGI) for its IRIX operating system in the early 1990s. It was later ported to Linux and released under the GNU General Public License (GPL). xfs_fsr has been a core component of the XFS toolset, providing online defragmentation capabilities crucial for maintaining performance on production systems.

xfs_info(8), xfs_admin(8), xfs_repair(8), xfs_growfs(8), xfs(5)