Patent ID: 7571264

Claim:
A computer system, comprising: a plurality of hosts; and a storage system coupled to the plurality of hosts, wherein the storage system includes a plurality of channel adaptors that couple with the plurality of hosts, a plurality of logical units that store data, and a storage load measuring module that measures a storage measured load for each channel adaptor, wherein each of the hosts includes one or more host bus adaptors that couple with the storage system, wherein at least one of the plurality of hosts includes an alternate path management module that manages paths through which the plurality of hosts access the logical units, wherein the alternate path management module includes: a host load measuring module that measures, for each logical unit and each channel adaptor, a host measured load caused by access from the at least one host to the logical unit; and an active path setting module that selects one of the channel adaptors for each logical unit based on the storage measured load measured by the storage load measuring module and the host measured load measured by the host load measuring module, and sets an active path passing through the channel adaptor, and wherein the active path setting module: calculates, for each channel adaptor, a host load caused by a host, other than the at least one host that includes the active path setting module, by subtracting the host measured load regarding the channel adaptor from the storage measured load; calculates, for each channel adaptor, a total value of the host load and the host measured load regarding the active path allocated to the channel adaptor; selects the channel adaptor having a smallest total value of the host measured load and the host load, and having a smallest calculated number of active paths; when there are a plurality of channel adaptors having the smallest total value of the host measured load and the host load, calculates the number of set active paths for each channel adaptor and selects the channel adaptor having the smallest total value of the host measured load and the host load and having the smallest calculated number of active paths; compares the host measured loads measured for the logical units with one another; and sets the active path of the logical unit of a largest host measured load before setting the active path of the logical unit of a smallest host measured load.