Patent ID: 8473704

Claim:
A storage device comprising: a processor; a main memory; and a plurality of memory devices that compose a plurality of storage volumes, where the memory devices are composed of a plurality of hard disk drive (HDD) units, wherein the processor, the main memory, and the HDDS are connected via an internal network, wherein: the main memory manages, with respect to each of the plural storage volumes having an unformatted area, a load per HDD unit that composes each of the storage volumes, and the processor determines, in accordance with a value of the load per HDD unit of the storage volumes, an order of priority for a sequential formatting process of the plural storage volumes, and executes the sequential formatting process with respect to an unformatted area of the plural storage volumes in accordance with the order of priority, the main memory further manages: a load threshold derived from an executable sequential formatting speed per HDD unit and a limit performance per HDD unit; with respect to each of the plural storage volumes having the unformatted area, an I/O penalty density indicating a frequency of incurred I/O penalties per unit of storage volume capacity; and map information indicating whether or not an area is already formatted; and the processor compares the load threshold and the loads of the storage volumes, divides the storage columns into a high-priority group and a low-priority group, executes the sequential formatting process with respect to the storage volumes belonging to the high-priority group in order of descending I/O penalty density, and then executes the sequential process with respect to the storage volumes belonging to the low-priority group in order of descending I/O penalty density; and the processor references the map information and determines whether or not an area corresponding to an access request from a host computer is an area that is already formatted, and, if the area is an unformatted area, executes a quick formatting process with respect to the unformatted area.