e2freefrag

Check free space fragmentation

$ e2freefrag [/dev/sdXN]

$ e2freefrag -c [chunk_size_in_kb] [/dev/sdXN]

e2freefrag [options] device

e2freefrag prints free space fragmentation information for ext2/ext3/ext4 filesystems. It shows how many free blocks are available as contiguous and aligned free space in histogram format.
The tool analyzes the filesystem's free space distribution, reporting statistics about chunk sizes and their frequency. This information helps assess filesystem health and determine if defragmentation might improve performance.
Useful for identifying fragmentation patterns that could impact sequential I/O performance, particularly on systems with large files or database workloads.

-c size

Chunk size in KB for histogram

Filesystem device to analyze

Filesystem should be unmounted or mounted read-only for accurate results. Part of e2fsprogs package.

e4defrag(8), dumpe2fs(8), e2fsck(8)