Patent ID: 7107421

Claim:
A data migration method from a first storage device to a second storage device in a computer system including said first storage device and said second storage device which provide volumes to a host computer via a switch, comprising the steps of: providing to said second storage device, a request for creating a destination volume having a size identical to the size of a source volume that is provided by said first storage device, allowing said second storage device to create said destination volume; carrying out data copy processing which stores data corresponding to data in said source volume into said destination volume; providing to said second storage device, a write protect request for said destination volume, and setting said destination volume as write protect, where the data in said source volume is copied, if the source volume is set as write protect; reading out the data in said source volume from said first storage device and the data in said destination volume from said second storage device, and comparing the two data items, if the destination volume is set as write protect; and providing a connection switching request to said switch, when it is indicated the data in said source volume agrees with the data in said destination volume, and carrying out switching of a target of said host computer, from said first storage device to said second storage device.