A storage system comprises a router, which receives and transfers commands; a plurality of RAID modules; and a switch, which receives commands from the router and transmits the commands to any of the plurality of RAID modules. Each RAID module comprises a plurality of media drives, a RAID group is provided by the plurality of media drives. Each RAID module comprises an independent RAID group which does not extend into other RAID groups. In the storage system, the router performs transfer of commands without performing analysis of commands, and a processor within the RAID module performs command analysis.