Patent ID: 8595737

Claim:
A method of deciding a migration method executed in a management server connected to a physical server to migrate a virtual server operated in a virtualization system which is operated in the physical server, wherein the management server stores, into a storage unit: physical resource information including maximum physical resource amount indicating performance of the physical server which operates the virtualization system; virtual resource information including occupied virtual resource coefficient indicating physical resource amount used by the virtual server and allocated physical resource coefficient indicating physical resource amount allocated to the virtual server in corresponding manner to the virtual server; and migration means information including variation ratio indicating degree of influence exerted by change of the occupied physical resource used by the virtual server on migration time required for migrating the virtual server by migration means and reference execution time required for migrating the virtual server by the migration means on the basis of predetermined occupied physical resource amount; and the method comprises the steps of: calculating occupancy amount of physical resource of the virtual server on the basis of the maximum physical resource amount of the physical server and the occupied virtual resource coefficient and the allocated physical resource coefficient of the virtual server; calculating change value of the occupied physical resource amount used by the virtual server being the target of migration on the basis of the calculated occupancy amount of physical resource and the predetermined occupied physical resource amount of the virtual server; and calculating the migration time required for migrating the virtual server by the migration means on the basis of the calculated change value, the variation ratio and the reference execution time.