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US 5,088,081 AGranted
Method and apparatus for improved disk access
AssigneePrime Computer, Inc.
InventorWilliam Farr
Life of this patent
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AssigneePrime Computer, Inc.
InventorWilliam Farr
Estimating the term…
In 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.
In a system including an array of disk drives comprising a plurality of disk drives connected to and controlled by a disk system controller, said disk drives having sectors for storing information in a digital format thereon, said information including a combination of digital data and digital redundant information, the redundant information allowing recovery of the digital data if a sector storing at least a portion of the digital information on one of the disk drives is defective, the improvement comprising:
In a system including an array of disk drives comprising a plurality of disk drives connected to and controlled by a disk system controller, said disk drives having sectors for storing information in a digital format thereon, said information including a combination of digital data and digital redundant information, the redundant information allowing recovery of the digital data if a sector storing at least a portion of the digital information on one of the disk drives is defective, a method of storing data on an additional reserve disk comprising the steps of:
An apparatus for storing digital data comprising:
Dependencies are inferred from the claim text.