Patent ID: 7069385

Claim:
A storage system comprising: plural first protocol transformation units that include interfaces with an external device and transform, to a protocol within the system, a read-write protocol of data exchanged with the external device; plural disk devices; plural second protocol transformation units that include interfaces with the disk devices and transform, to the protocol within the system, a read-write protocol of data exchanged with the disk devices; plural cache control units that include cache memories storing data read/written with respect to the disk devices and control the cache memories; an interconnection network connecting the first protocol transformation units, the second protocol transformation units and the cache control units; and a system management unit, wherein the plural cache control units and the plural second protocol transformation units are divided into plural control clusters where a single control cluster includes an optional number of the cache control units and the second protocol transformation units, only data stored in the plural disk devices connected to the second protocol transformation units in the control clusters is stored in the cache memories of the cache control units in the control clusters, control of the cache memories and management of storage regions of the plural disk devices are independent inside the control clusters, and the system management unit manages, as a single system, the plural first protocol transformation units and the plural control clusters.