Patent ID: 7299322

Claim:
A storage device used for a computing system that includes a host computer identifying a volume thereof with an intra-host identifier (ID) and said storage device that identifies said volume thereof with an intra-storage ID comprising: a volume pair control table to control volume pairs that execute copy among plural volumes; an input/output (I/O) receiving process unit to receive a switching command, from said host computer, that makes correspondence between said intra-host ID of a switching source volume and identification information of a switching target volume; an I/O target search process unit to search said switching target volume, from said volume tables, that is identical to identification information of said switching target volume receipt among switching target candidate volumes that form said volume pair relation with said switching source volume; an I/O target memory process unit to memorize said intra-host ID of said switching source volume and said intra-storage ID of said switching target volume after being searched in a switching table with corresponding therebetween; and an I/O processing unit to acquire said intra-storage ID of said switching target volume in reference to said switching table in case of receiving an access request such that said intra-host ID of said switching source volume is used as a key, and executes switching to access to said switching target volume.