First you need to distinguish between the ones that just give you some kind of blob api (HDFS, mogilefs, whatever sector/sphere's FS component is), and mostly-p

First you need to distinguish between the ones that just give you some kind of blob api (HDFS, mogilefs, whatever sector/sphere's FS component is), and mostly-posix-compliant ones (glusterfs, ceph, etc). http://pl.atyp.us/wordpress/?p=2662 http://pl.atyp.us/wordpress/?p=2662 gives some details on the 2nd category, so that's probably more useful in a discussion about ceph.