[lmm]

Sounds like the kind of problem OrientDB is supposed to solve (I haven't tried it though). I would stay away from network filesystems (they're fiddly, they'll add much more operational overhead than a database product, and there is no mature distributed one. OpenAFS is probably your best bet if you do want to go that route).

[mavelikara]

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.

[lmm]

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.

[mikojava]

that's very interesting. I've heard the exact opposite, hazelcast is easy to work with and Zookeeper more complicated.