Patent ID: 8140472

Claim:
A storage controller, which is connected to a storage system that manages a plurality of types of logical units and a client that sends a file access request, and which, based on the file access request from the client, sends to the storage system a read access request or write access request that specifies a logical unit that has been allocated to a logical volume corresponding to a file system space in which a file subjected to a target of the file access request is stored, the controller comprising: a creation module that creates a logical volume; a management module that manages a plurality of types of logical units including: a first type logical unit that is a logical unit associated with physical storage regions on a hard disk drive of the storage system; a second type logical unit that is a logical unit associated with virtual storage regions to which the physical storage regions are dynamically allocated in accordance with the occurrence of receiving a write request to one of the virtual storage regions to which none of the physical storage regions are allocated; a third type logical unit that is a logical unit associated with physical storage areas on a flash memory device of the storage system; and a fourth type logical unit that is a logical unit associated with virtual storage areas to which the physical storage areas are dynamically allocated in accordance with the occurrence of receiving a write request to one of the virtual storage areas to which none of the physical storage are allocated; a measurement module that measures an access characteristic for each logical volume; a decision module that decides a type of a logical unit to be allocated to the logical volume, based on the measured access characteristic; and an allocation module that allocates, from among the plurality of types of logical units, a logical unit of the type decided by the decision module to the logical volume, wherein the decision module: (1-1) decides on the first type logical unit when a proportion of read accesses in a read/write ratio is small, and a data quantity increase rate is large; (1-2) decides on the second type logical unit when the proportion of read accesses in the read/write ratio is small, and the data quantity increase rate is small; (1-3) decides on the third type logical unit when the proportion of the read accesses in the read/write ratio is large, and the data quantity increase rate is large; and (1-4) decides on the fourth type when the proportion of read accesses in the read/write ratio is large, and the data quantity increase rate is small.