It's been a while since last running any Linux file-system tests on a hard drive considering all of the test systems around here are using solid-state storage and only a few systems commissioned in the Linux benchmarking test farm are using hard drives, but with Linux 4.0 around the corner, here's a six-way file-system comparison on Linux 4.0 with a HDD using EXT4, Btrfs, XFS, and even NTFS, NILFS2, and ReiserFS.