Patent ID: 7844794

Claim:
A method for controlling storage system in which a first storage controller is connected to a storage device in a second storage controller and the first storage controller is configured to be able to read and write data from to the storage device in the second storage controller in response to a request a request from a host device connected to the first storage apparatus, comprising the steps of: controlling data transmission and reception between the host device and the storage device in the second storage controller; temporarily storing the data in a cache memory in the first storage controller; setting a threshold value for storage capacity in the cache memory assigned to the storage device according to at least one of the class of a storage control speed of the second storage controller, a version of a controller in the second storage controller, and a storage capacity of a cache memory in the second storage controller; limiting access to the cache memory based on the usage state of the storage device; reducing the threshold value when a specific failure occurs in the storage device at a specific frequency; and determining a value subtracted from the threshold value based on the alternate path structure type in the storage device and the redundancy of the alternate paths.