Patent ID: 7853765

Claim:
A storage apparatus coupled to a host system and another storage apparatus, which have a plurality of logical volumes and a processor, comprising: a plurality of logical volumes, a processor which allocates a storage extent of a first volume of said plurality of logical volumes in said storage apparatus to a virtual volume when said storage apparatus receive a write request to said virtual volume from said host system, wherein said virtual volume of said storage apparatus is pair-configured with a second logical volume of said a plurality of logical volumes in said another storage apparatus, said processor of said another storage apparatus sends data written by said host system into said virtual volume to said second volume in said another storage apparatus, so that said data is written into said second volume, wherein said processor of said storage apparatus, in a initial copy procedure, sends a data of value 0 to an address position in said second volume corresponding an address position in said virtual volume that has not been allocated to said first volume, and sends a data stored in said virtual volume to an address position in said second volume corresponding an address position in said virtual volume that already has been allocated to said first volume.