OrientDBs clustering is, IIRC, built on top of Hazelcast. Storing my files in a clustered Hazelcast is another option I am considering, although I forgot to include it in my first comment.
Oh yuck. I didn't know that. I've long found Hazelcast a pain to work with.
Having seen in a sibling comment that you're talking about very small files, I'd recommend Zookeeper - it's mature and has pretty low admin overhead, IME.
