Patent ID: 7120738

Claim:
A storage system comprising: a plurality of host adaptors, which can be coupled to at least one host device, and which form interfaces for the host device; a plurality storage devices for storing therein data transferred from the host device; a plurality of disk adaptors coupled to said storage devices, which form interfaces for said storage devices; a cache for temporarily storing therein data transferred between said host adaptors and said disk adaptors; two buses, coupled to said host adaptors, said disk adaptors, and said cache, which transfer data among said host adaptors, said disk adaptors, and said cache, wherein said two buses operate as a pair of buses having a transfer ability larger than one of said two buses; a memory for storing information indicating status which of said two buses is available for use due to a failure in the other of said two buses, wherein each of said host adaptors includes a format converter for converting data of a count key data (CKD) format, in a case where one of said host adaptors, being coupled to a host device, receives the data of the CKD format from the host device, into data of a fixed block architecture (FBA) format suitable for storage in said storage devices before being stored in said cache and sending the converted data of the FBA format to said cache through said two buses, wherein said cache stores the converted data of the FBA format converted by said format converter, and wherein upon failure one of said two buses is used based on said status information stored in said memory.