Patent ID: 8498997

Claim:
A method of migrating a virtual server image in a system which includes a first site, a second site, and a third site, the first site having a first server and a first storage system coupled to the server via a first network, the second site including a second server and a second storage system coupled to the second server via a second network, the third site being coupled to the first site and the second site, the third site having a plurality of gold images, the virtual server image being migrated using the gold images, the method comprising: storing, by the first storage system, a first gold image at the first storage system; creating, by the first storage system, a first snapshot volume at the first storage system based on the first gold image, the first gold image corresponding to a first gold image ID; sending, by the first storage system, the first gold image ID, update data of the first gold image, and address information for the update data, from the first storage system to the second storage system; checking whether a gold image corresponding to the first gold image ID is at the second site; when the gold image corresponding to the first gold image ID is at the second site, storing, by the second storage system, the gold image corresponding to the first gold image ID as a second gold image at the second storage system; when the gold image corresponding to the first gold image ID is not at the second site, obtaining, by the second storage system, a third gold image corresponding to the first gold image ID from the third site by specifying the first gold image ID, and storing the third gold image as a second gold image at the second storage system; creating, by the second storage system, a second snapshot volume at the second storage system based on the second gold image corresponding to the first gold image ID; allocating, by the second storage system, storage for storing the update data at the second storage system with reference to the address information; and storing, by the second storage system, the update data in the allocated storage.