GlusterFS & Ceph

GlusterFS is easier to set up. Natively a file store with objects being added by other tools. Gluster builds on top of filesystems (mostly XFS) but needs to be tuned or it runs like shit.

Ceph is more complicated and has more moving parts. Uses a hashing system ("CRUSH") to determine where files go, so files may need to be shuffled between servers during rehashings. Natively an object store with files being added layers. Basically needs a dedicated block device these days as it bypasses the filesystem entirely.