Data prefetch in storage device

A meta data server , a user node and a storage device are connected together via a Fibre channel and a LAN to configure a NAS over SAN system. The user node sends out a request to access the data in each file. The file is stored in the storage device in blocks of default size. The meta data server informs the user node of the block number where the file to be accessed is stored based on meta data in which relationship between a file and a block is recorded. Prior to this processing, the meta data server instructs the storage device to cache the data in advance. This application enables the storage device to provide the data promptly in response to read request from the user node