Patent ID: 7017007

Claim:
A disk array device comprising: a channel adapter connected to a host device and an external device via a communications port for controlling the exchange of data with the host device and said external device; a disk adapter for controlling the exchange of data with a memory device; a cache memory used by said channel adapter and said disk adapter; one or more logical system partitions which are constructed by logically dividing resources provided by said channel adapter, said disk adapter, said memory device and said cache memory; a transfer amount detection part which detects the amount of data transferred to said external device from said logical system partitions for each of said logical system partitions; and a data transfer control part which compares a specified value that is preset for each of said logical system partitions and the data transfer amount detected by said transfer amount detection part, and performs band control that limits the transfer of data from said logical system partitions to said external device in cases where the data transfer amount exceeds said specified value, wherein said data transfer control part limits data transfer by delaying the response to a data write request from said host device by a specified preset time when said data transfer amount exceeds said specified value.