Patent ID: 6851022

Claim:
A RAID controller, which accesses an access request area on logical volumes distributed and stored on a plurality of physical disks according to a disk access request from a host device, comprising: a plurality of physical disk groups storing different logical volumes, wherein one logical volume is distributed to a plurality of physical disks to form a plurality of redundant groups; a plurality of management modules managing said plurality of redundant groups-included on said plurality of physical disks, and issuing a logical format processing request for logical formatting of each said disk access request area of each of said logical volume distributed to said plurality of physical disks forming said redundant groups, by referring to one of a plurality of management tables for managing progress information of said logical format of each of said logical volume distributed to said plurality of physical disks forming said redundant groups; and a plurality of lower layer modules for accessing one of said plurality of physical disks according to the processing of said logical format processing request of said plurality of management modules, wherein each said management module comprising: one of said plurality of said management tables managing said plurality of redundant groups; and a queue queuing said disk access request, and wherein each of said plurality of management modules, according to said disk access request, judges whether each of said access request area has been logically formatted referring to one of said plurality of management tables, and when judged as formatted, requests each of said disk access requests to said plurality of lower layer modules, and when not formatted, issues a logical format processing request and queues said disk access request in said queue, and wherein when no disk access request exists in said queue, searches an unformatted area from one of said plurality of management tables, and issues a logical format processing request to said plurality of lower layer modules.