Content Serving Cluster
vlisivka: I recommend to look at GlusterFS. It fast, modularized, layered clustering file system. It is not tied to Linux kernel because it built for (patched) Fuse. With Infiniband hardware, it is fastest clustered system available for free. See  http://www.gluster.org/docs/index.php/GlusterFS_1.3.pre2-VER...  for example.