Patent ID: 7210021

Claim:
A cache control program to be executed by a file controller including a disk device that records a plurality of objects accessed by a client machine and a cache section that stores a copy of at least one of the objects, wherein when the client machine tries to access one of the objects recorded in the disk device, the file controller sends the copy of said object to the client machine if the copy of said object is in the cache section, and wherein each object is one of a primary object, a secondary object, and a tertiary object, the tertiary object being configured by at least one secondary object, the secondary object being configured by at least one primary object, and the primary, secondary, and tertiary objects configuring different hierarchical levels, the cache control program controlling the file controller, the cache control program when executed comprising the steps of: managing the cache section as a plurality of cache extents; generating a plurality of cache IDs, each including a hierarchical level of an object and an object identification used to identify the objects of each hierarchical level from each other; generating a cache header table indicating the relation of the cache IDs and the cache extents in each hierarchical level, wherein the cache header table contains cache headers that hold the cache IDs and a plurality of keys, each being unique and used for one of the cache IDs; and searching the cache header table when the client machine tries to access one of the objects recorded in the disk device with the cache ID and the key of said object.