Patent ID: 7464224

Claim:
A data migration method in a virtualization system coupled to first, second and third storage subsystems which store data written by a host device, each of the first, second and third storage subsystems presenting at least one storage volume configured with a plurality of physical storages as a storage resource to the virtualization system, the virtualization system presenting virtual volumes corresponding to the storage volumes as storage resources to the host device, the method comprising: classifying the virtual volumes into first, second and third classes according to a predetermined criteria; mapping a first storage volume to a first virtual volume classified as the first class so as to present the first storage volume via the first virtual volume to the host device, the first storage volume being configured with a plurality of physical storages in the first storage subsystem; gathering activity information relating to I/O activity and presenting the activity information in connection with the first virtual volume to a user; determining, based on the activity information, whether to migrate the data stored in the first storage volume to the second class or the third class; and migrating data stored in the first storage volume to a second storage volume or a third storage volume, wherein the second storage volume is configured with a plurality of physical storages in the second storage subsystem and mapped to a second virtual volume classified as the second class so as to present the second storage volume via the second virtual volume to the host device, wherein the third storage volume is configured with a plurality of physical storages in the third storage subsystem and mapped to a third virtual volume classified as the third class so as to present the third storage volume via the third virtual volume to the host device.