GlusterFS is a clustered file-system capable of scaling to several
peta-bytes. It aggregates various storage bricks over Infiniband RDMA
or TCP/IP interconnect into one large parallel network file
system. GlusterFS is one of the most sophisticated file system in
terms of features and extensibility. It borrows a powerful concept
called Translators from GNU Hurd kernel. Much of the code in GlusterFS
is in userspace and easily manageable.

Please visit http://www.gluster.org/docs/index.php/GlusterFS for more info.