Patent ID: 7536527

Claim:
A method for migrating data from a first storage system having a plurality of first logical volumes to a second storage system having a plurality of second logical volumes, wherein a plurality of host computers are coupled to the first storage system and the second storage system, the method comprising steps of: managing a plurality of migration groups each including at least one first logical volume of the first logical volumes, at least one second logical volume of the second logical volumes, and at least one host computer of the host computers in an un-transferred phase; based on a certain migration group specified from the plurality of migration groups, sequentially changing access routes of the at least one host computers included in the certain migration group by sequentially changing an indication of an access destination storage system for each of the certain host computers from the first storage system to the second storage system to permit the each of the certain host computers to access the second storage system in a route-changing phase; accessing the first storage system by the second storage system in response to an access request from one of the certain host computers, for which an access route is changed, when the second storage system receives the access request during the step of sequentially changing the access routes; and after the step of sequentially changing the access routes, migrating data from the at least one first logical volume included in the certain migration group to the at least one second logical volume included in the certain migration group in a data transferring phase, wherein information indicating relationships between each of said phases and identifiers of the groups of logical volumes on the old storage subsystem and the new storage subsystem are stored in a table which is stored in a management system connected to the old storage subsystem and the new storage subsystem, and wherein said route changing phase and said data transferring phase are conducted according to groups of logical volumes based on said information indicating relationships in said table.