Cluster-based cache memory allocation

Abstract

The present invention relates to a disk drive including a cache memory having a plurality of sequentially-ordered memory clusters for caching disk data stored in sectors (not shown) on disks of a disk assembly. The disk sectors are identified by logical block addresses (LBAs). A cache control system of the disk drive comprises a cluster control block memory, having a plurality of cluster control blocks (CCB), and a tag memory, having a plurality of tag records, that are embedded within the cache control system. Each CCB includes a cluster segment record with an entry for associating the CCB with a particular memory cluster and for forming variable length segments of the memory clusters without regard to the sequential order of the memory clusters. Each tag record assigns a segment to a continuous range of LBAs and defines the CCBs forming the segment. Each segment of the memory clusters is for caching data from a contiguous range of the logical block addresses. The cache control system efficiently exploits available memory clusters for responding to host commands.