Patent ID: 7680953

Claim:
A computer system adapted to be coupled to one or more host computers and a name server, the one or more host computers having a function to search for an alternate path when a defect is discovered in a path used for reading/writing data from/to at least one of a plurality of storage devices, the computer system comprising: a first storage device of the plurality of storage devices having a first port including a first target communicating with the one or more host computers through the first port, a first target address identifying the first target being registered to the name server, a second storage device of the plurality of storage devices having a second port including a second target for communicating with the one or more host computers through the second port, wherein the first storage device has a function for migrating data from a migration source target to a migration destination target and ordering the migration destination target to reject new update instructions and reflect data updated during migration, wherein the first storage device has a registration change function for changing the first target address, of the first target as the migration source target, registered in the name server to a second target address identifying the second target, as the migration destination target, of the second storage device, if data stored in the first storage device is migrated to the second storage device, wherein the first storage device has a function for disconnecting communications including a connection between the migration source target and the host computer, denying a re-connection request of the migration source target and rejecting a new login to the migration source target, for reading/writing data from/to the first storage device, established by the one or more host computers with the first target as the migration source target subsequent to the registration change process, and wherein the registration change function causes to change by detecting that a processing quantity of the first target as the migration source target has exceeded a value.