Patent ID: 8566541

Claim:
A storage system, comprising: a plurality of physical storage devices upon which is based a pool, that is a storage region made up from a plurality of physical regions; and a controller coupled to a plurality of computers and to said plurality of physical storage devices; wherein a common electronic object is used by said plurality of computers; said controller supplies to said plurality of computers a plurality of duplicate volumes, that are a plurality of virtual volumes corresponding to duplicates of a master volume, that is a virtual volume in which said electronic object is stored; each virtual volume is a virtual logical volume that follows sync provisioning, and comprises a plurality of virtual regions; in said plurality of duplicate volumes, a plurality of physical regions that are allocated to said master volume are allocated, and that plurality of physical regions store said electronic object that is stored in said master volume; said plurality of computers comprise a first computer and a second computer; a first duplicate volume is supplied to said first computer, and a second duplicate volume is supplied to said second computer; wherein said controller is configured to: (A) receive, from said first computer, a write command in which is specified a write destination address in said first duplicate volume, that is a command in which an electronic module that is applied to the electronic object used by said first computer is specified as being the write subject; (B) copy, to a second physical region within said pool, data within a first physical region that is allocated to a virtual region of the write destination to which said write destination address belongs, write said electronic module to said second physical region, and allocate said second region to a virtual region of said write destination, instead of said first physical region; (C) allocate said second physical region to a virtual region within said second duplicate volume corresponding to a virtual region of said write destination, instead of the physical region that is allocated to that virtual region; (F) for a first master volume, decide whether or not the duplicate volume load is high; and (G) when the result of said decision (F) is affirmative, perform the processing described below: (g1) copying data in a first physical region allocated in said first master volume, to a third physical region; (g2) creating a second master volume to which said third physical region is allocated; and (g3) creating a duplicate of said second master volume, in which said third physical region is allocated.