Patent ID: 8918551

Claim:
A storage system coupled to a host computer, comprising: a management computer; a plurality of storage devices that are provided as a plurality of logical storage devices to the host computer; a plurality of interface packages, each of the plurality of interface packages coupled to the management computer and comprising at least one interface unit; a shared memory that stores control information for the plurality of logical storage devices, said control information including ownership information for the logical storage devices; a plurality of micro-processor packages, each of the plurality of micro-processor packages comprising at least one micro-processor; wherein each interface unit comprises management information for managing the plurality of micro-processor packages, said micro-processor package in-charge of controlling input/output processing for the storage area of the logical storage devices, and a process that transfers an input/output request to a micro-processor package that is in-charge of the input/output processing for a logical storage device based on the management information when the input/output request for the logical storage device is received from the host computer; wherein each of the plurality of micro-processor packages: (1) receives a request for changing ownership from a first micro-processor package, which is in charge of a logical storage device whose load is higher than other logical storage devices, to a second micro-processor package whose load is lower than other micro-processor packages; and (2) sets the management information and the control information such that the second micro-processor package is in charge of a logical storage device which the first micro-processor package was in charge of; and wherein the management computer: (1) receives a request for changing an interface package; (2) requests the micro-processor package, to delete at least one path definition between the logical storage devices and interface units being replaced; (3) confirms a replacement of interface package; and (4) requests to the micro-processor package, to set the path definition between the logical storage devices and interface units of new interface package.