System and method for selective write-back caching within a disk array subsystem
November 13, 2015. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesMethod and circuit for programmable selecting a variable sequence of element using write-back Write-back cache with ECC protection Method for controlling disk array operations by receiving logical disk requests and translating the requests to multiple physical disk specific commands Disk array system Storage device array architecture with copyback cache Disk drive array with efficient background rebuilding Method and apparatus for incorporating cache line replacement and cache write policy information into tag directories in a cache system Redundant array parity caching system Method and circuit for programmably selecting a variable sequence of elements using write-back Fast updating of DASD arrays using selective shadow writing of parity and data blocks, tracks, or cylinders InventorAssigneeApplicationNo. 557671 filed on 11/13/1995US Classes:714/6Redundant stored data accessed (e.g., duplicated data, error correction coded data, or other parity-type data)ExaminersPrimary: Beausoliel, Robert W. Jr.Assistant: Elmore, Stephen C. Attorney, Agent or FirmInternational ClassG06F 012/16AbstractA fault tolerant disk array subsystem is provided that includes a plurality of data drives for storing real data and a parity drive for storing redundant data. Each data drive is associated with a dedicated write-through cache unit and the parity drive is associated with a dedicated write-back cache unit. An array scheduler schedules read and write operations to access the data drives and includes a parity control unit for updating parity information when new data is written to one of the data drives. Since a write-back caching technique is used to store updated parity information, the write latency of the parity drive does not limit the write-throughput of the disk array subsystem. Furthermore, since a non-volatile memory unit is provided to store the addresses of any dirty parity information within the write-back cache unit, parity information can be reconstructed in the event of a power failure. The disk array subsystem provides a low cost, mass storage resource having improved write performance characteristics. The disk array subsystem also accommodates data redundancy to allow data restoration in the event of disk failure. | |
