Patent ID: 7996640

Claim:
A computer system comprising: a storage system including a plurality of storage apparatuses, each providing volumes; a host computer accessing the storage system via a network; and a management computer monitoring the plurality of storage apparatuses, wherein the management computer manages a resource group associated with migration source volumes, wherein the management computer stores migration management information which includes migration statuses of the migration source volumes to migration destination volumes, and identifiers of alternate migration destination volumes corresponding to the migration source volumes, and wherein, during migration of the migration source volumes to the migration destination volumes, the management computer: detects a certain status of the storage system according to the monitoring of the plurality of the storage apparatuses; queries a user to change migration destinations of the migration source volumes, from the migration destination volume to the alternate migration destination volumes; and changes migration destinations of the migration source volumes, from the migration destination volumes to the alternate migration destination volumes, if the management computer receives instruction of change execution, wherein the resource group includes a first sub-group and a second sub-group, wherein the first sub-group is associated with first migration source volumes which are two or more of the migration source volumes and which are in a first storage apparatus, and the second sub-group is associated with second migration source volumes which are two or more of the migration source volumes and which are in a second storage apparatus, wherein the management computer stores a plurality of change migration destination plans corresponding to the resource group, each of which indicates an event type and a nature of a control process, wherein the nature of the control process in one of the plurality of change migration destination plans is the change migration destination, and wherein, based on an instruction from a user, the management computer does not change the migration destination about the first sub-group or the second sub-group which is not related to the certain status of the storage system.