Patent ID: 7945731

Claim:
A data reading method of enabling a computer coupled to a storage system to read data out of a logical disk drive which is provided by the storage system and includes a plurality of physical disk drives, the method comprising the steps of: obtaining, when a given condition is met, by the computer, first mapping information which shows a relation between addresses in the plurality of physical disk drives in the storage system and addresses in the logical disk drive; constructing, from the obtained first mapping information, second mapping information which associates the addresses in the logical disk drive which are recognizable to the computer with the addresses in the plurality of physical disk drives in the storage system; creating, by the computer, a queue for each of the plurality of physical disk drives from the second mapping information; identifying, upon reception of a plurality of read requests, which ones of the plurality of physical disk drives store the data requested by the plurality of read requests, and accumulating the plurality of read requests in respective queues of the identified physical disk drives; and issuing, after the plurality of read requests accumulated in the respective queues of the plurality of physical disk drives are reallocated into an order that shortens data read time of the plurality of physical disk drives, the plurality of read requests from the queues to the storage system, wherein, in the step of obtaining the first mapping information which shows the relation of the addresses in the logical disk drive, the computer obtains identification information of the first mapping information and obtains the first mapping information, when the obtained identification information differs from the identification information obtained last time.