So far the best option I've found has been GlusterFS
That gives it some credibility. Especially ability to deal with tough challenges they'll encounter in this domain. Helps to have encountered most already. ;) I'll look at it in more detail later on. I'm also more interested in it if it has many-node, HA/SSI support. What's ETA on that feature?
We are also about to finish distributed server functionality you can track the work here https://github.com/minio/minio/tree/distributed