Howtoforge shows you how to combine four single storage servers (running CentOS 6.3) to a distributed replicated storage with GlusterFS

This tutorial shows how to combine four single storage servers (running CentOS 6.3) to a distributed replicated storage with GlusterFS. Nodes 1 and 2 (replication1) as well as 3 and 4 (replication2) will mirror each other, and replication1 and replication2 will be combined to one larger storage server (distribution). Basically, this is RAID10 over network. If you lose one server from replication1 and one from replication2, the distributed volume continues to work. The client system (CentOS 6.3 as well) will be able to access the storage as if it was a local filesystem. 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. Storage bricks can be made of any commodity hardware such as x86_64 servers with SATA-II RAID and Infiniband HBA.

  Distributed Replicated Storage Across Four Storage Nodes With GlusterFS 3.2.x On CentOS 6.3