MogileFS is our open source distributed filesystem.

http://danga.com/mogilefs/

Some of the advantages are

• No Single point Failure
• Automatic file replication
• Better than RAID
• Shared-Nothing — MogileFS doesn’t depend on a pricey SAN with shared disks. Every machine maintains its own local disks.
• No RAID required — Local disks on MogileFS storage nodes can be in a RAID, or not. It’s cheaper not to, as RAID doesn’t buy you any safety that MogileFS doesn’t already provide.