Ceph is a system daemon which publishes a reliable distributed block storage, also published as an S3-compatible object storage API via a proxy.
There is a Ceph Cluster in a LAN maintained by allmende.io for circus.dev.
Interesting use cases are (1) as a backend for Deis and (2) as a transparent, "scale-out" NAS via CephFS.
RBD support for qemu/libvirt KVM similar to Deis
Also see Ceph on Raspberry Pi 2 and Gigabit networking for Raspberry Pi 2 for ways to work around Ethernet and USB 2.0 I/O deficiencies.