Method and apparatus for improved disk access
Patent 5088081 Issued on February 11, 1992. Estimated Expiration Date: 
March 28, 2010. 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.
March 28, 2010. 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 of recording in a disk memory and disk memory system Memory unit backup using checksum Method for substituting replacement tracks for defective tracks in disc memory systems Disk drive memory Patent #: 4914656 InventorAssigneeApplicationNo. 500729 filed on 03/28/1990US Classes:369/47.14, By medium defect indicative control signal360/24, SPLITTING, PROCESSING AND RECOMBINING ONE INFORMATION SIGNAL FOR RECORDING OR REPRODUCING ON THE SAME TRACK360/47, Redundant or complimentary tracks369/53.42, Having abnormality condition indicating714/7Reconfiguration (e.g., adding a replacement storage component)ExaminersPrimary: Envall, Roy N. Jr.Assistant: Hindi, Nabil Attorney, Agent or FirmInternational ClassesG11B 007/00G11B 005/09 AbstractIn a RAID level 5 disk drive subsystem, one or more additional disk drives, called "reserve" disks are intercoupled to the array of disk drives and a control system is included for storing recovered digital data on the additional disk drive if a sector on one of the disk drives becomes defective. The system reduces the number of disk accesses required to obtain the information stored on the defective sector. Once the information has been recovered, it is then stored on the "reserve" disk. Thereafter, whenever this information is required, the system reads the required information from the "reserve" disk, instead of going through an entire recovery process for the defective sector. Since the recovery process can take a time that is greater than several disk access times, the present invention improves the speed and the availability of data. In another embodiment of the invention, a bitmap memory is used wherein bits in the bitmap memory representing sectors may be set to indicate whether or not sectors are defective. In a further embodiment of the invention, a disk drive tester, which can be embodied in either hardware or software, is incorporated into the apparatus for periodically testing the "reserve" disk.Other References
Field of SearchSPLITTING ONE INFORMATION SIGNAL FOR RECORDING ON PLURAL DISTINCT TRACKS OR REPRODUCING SUCH SIGNALSPLITTING, PROCESSING AND RECOMBINING ONE INFORMATION SIGNAL FOR RECORDING OR REPRODUCING ON THE SAME TRACK RECORDING OR REPRODUCING AN INFORMATION SIGNAL AND A CONTROL SIGNAL FOR CONTROLLING ELECTRONICS OF REPRODUCER Redundant or complimentary tracks | |
