Storage Technology Corporation

Alan R Permut

John Timothy O'Brien

George A Rudeseal

Jay S Belsan

Hendrikus Everhardus Vandenbergh

Keith Allen Radebaugh

A method for detecting and remembering multiple sequential access patterns made from a host to a memory system having one or more logical storage devices. Once a sequential access pattern is detected, one or more tracks are requested to be prestaged ahead of the current access request. The number of tracks requested to be prestaged ahead may be responsive to the amount of storage available in the cache memory. One list is provided for each logical storage device. Each list has multiple entries and is logically divided into two parts. A sequential part contains entries for access streams which the system has determined are sequential and for which the system may have prestaged one or more tracks into cache. A candidate part contains information about recent host accesses which have not as yet been determined to be sequential. The entries within each of the two parts of the list are logically ordered in a most-recently-used fashion. The division between the two parts of the list is allowed to change so that although the total number of entries may be held constant, the proportion of the entire list allocated to each of the two parts can be varied. Inactive entries in the list are invalidated over time.

Sequential detection and prestaging methods for a disk storage subsystem

One or more background processes that references data storage volumes and cylinders that are to be scrubbed to ensure the integrity of the data stored thereon. A priority scrubbing process is also available to note data storage volumes that have recently had data written thereon by the host processor and which require a more timely review of the data than less frequently used volumes.

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Louisville, CO, United States of America

Alan R Permut