Patent ID: 7624306

Claim:
A storage system, comprising: a plurality of host devices; a plurality of storage devices for storing data; at least one storage controller to exclusively control writing data received from the host devices into a group of the storage devices; a unit connected between said at least one storage controller and said host devices and operating as a switch, said unit including: a plurality of communications ports each connected to said at least one storage controller or one of the plurality of host devices respectively, a buffer area for temporarily storing data received from said at least one storage controller or said plurality of host devices via the plurality of communications ports, a trace data storage area for storing trace data, and a processor which stores information related to said data received via said plurality of communications ports in said trace data storage area as said trace data, reads out the trace data stored in said trace data storage area, and transmits the read trace data to said at least one storage controller, wherein said at least one storage controller receives and accumulates a plurality of said trace data to generate a trace data list, said trace data list includes said accumulated trace data listed by a destination ID, and a source ID, and at least one of a detection time, a differential time, a communications port number, storage controller information, host device information of said data received by the unit, said data received by the unit is a data frame which at least includes said destination ID, and said source ID, and a pay load, said trace data is obtained by striping said pay load from said a data frame, and said data frame further includes an option, and said trace data is obtained by further striping said option from said a data frame.