Patent ID: 7571280

Claim:
A storage system comprising: a protocol transformation unit connected to an external device and transferring a read/write request sent from an external device; a hard disk device; a disk adapter that connects the hard disk device to a communications path; and a plurality of clusters each including at least one cache adapter connected to the communications path, wherein the cache adapter connects said protocol transformation unit with the disk adapter, the cache adapter has a first processor, a cache memory that stores a copy of at least some of data stored in the hard disk device, and a shared memory that stores commands for accessing the cache memory, said first processor is configured to access the cache memory and the shared memory in the cache adapter, and conducts cache hit/miss control based on said read/write request sent from the protocol transformation unit, a second processor is located in the protocol transformation unit and configured to receive a command to conduct a command analysis, the second processor is configured to conduct the command analysis by accessing the cache adapter, referencing a logical unit allocation management table stored in the shared memory, and allocating the cache adapter which is managing a virtual volume configuring a logical unit in which the requested data is recorded during a request destination determination, and the second processor is configured to access of at least another cache adapter which is also managing the virtual volume configuring the logical unit in which the requested data is recorded during a request destination determination.