Howtoforge posted a tutorial about setting up GlusterFS 3.2.x on CentOS 6.3

This tutorial shows how to set up a high-availability storage with two storage servers (CentOS 6.3) that use GlusterFS. Each storage server will be a mirror of the other storage server, and files will be replicated automatically across both storage servers. 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.

  High-Availability Storage With GlusterFS 3.2.x On CentOS 6.3 - Automatic File Replication (Mirror) Across Two Storage Servers