There is Sheepdog distributed file system which recently went into version 1.0. Sheepdog is similar to Ceph but seem simpler to operate.

For distributed object storage: I have also used MooseFS,LizardFS distributed object storage and MooseFS,Lizard runs very steady on production work loads. Steady as setup and then no ops issues.

Also to the short list is BeeGFS, BeeGFS is created by Fraunhofer is seriously fast distributed file system.