Patent ID: 7996639

Claim:
A computer readable program code module for a virtualization system stored on a computer readable storage medium, wherein the virtualization system is coupled to a plurality of storage subsystems which store data written by a host device, each of the plurality of storage subsystems presenting a data storing area configured with a plurality of physical storages as a storage resource to the virtualization system, which is configured to map a first migration group, the first migration group comprising a first portion of a data storing area defined as a first tier and a second portion of a data storing area defined as a second tier, the computer readable program code module comprising code executable by a processor to perform a method comprising the steps of: displaying current tier positions of the first migration group; displaying tier positions to which one of the current tier positions may be migrated; receiving information from a user specifying to which tier position the one of the current tier positions is to be migrated; and displaying the tier position after migration, wherein the migration is executed by migrating data in the first migration group to a second migration group, the second migration group comprising a third portion of a data storing area defined as a third tier and a fourth portion of a data storing area defined as a fourth tier, and wherein a relationship of tier position between the third tier and the fourth tier is based on a relationship of tier position between the first tier and the second tier.