US 6,785,788 B1Granted

System and method for implementing an enhanced raid disk storage system

AssigneeUnisys Corporation

InventorWilliam H. Sands, III

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Abstract

Improved systems and methods for storing data, wherein data stored on one or more disks of a first capacity is mirrored to one or more disks of a second, larger capacity. According to the invention, one or more disk drives of a first capacity may be coupled to create a virtual volume. One or more disks of a second, larger capacity are then used to provide a single larger volume or multiple larger volumes that serve as the mirroring drive or drives for the array of smaller drives. Data from the smaller drives is stacked in stripes sequentially across the larger drive(s). Alternately, data from the smaller drives may be striped in zones across the larger drive(s). In yet another embodiment, the asymmetric nature of the mirroring technique of the present invention can be used in reverse, wherein an array of smaller capacity drives serve as the mirror for one or more larger capacity drives.

Claims14

Dependent claims

In a computer system, a method for storing data on a plurality of disk drives, said method comprising:

(1) providing a plurality of disk drives for storing said data,
(2) providing a single second disk drive having a storage capacity at least equal to the total storage capacity of said first disk drives, said second disk drive providing for mirroring of data stored on said first disk drives,
(3) simultaneously writing each of a plurality of data sets on a respective one of said first disk drives and also writing a direct image of each data set in a respective area of said second disk drive such that data coherency is maintained between data sets written on said first disk drives and their respective direct images written on said second disk drive without requiring said first or second drives to be initialized;
(4) reading a data set by accessing the first disk drive on which the data set is stored and outputting the data set to said computer system;
and
(5) if the data set is unavailable from said first disk drive then accessing its corresponding direct image from its respective area on said second disk drive for outputting to said computer system.

3 more elements

Dependencies are inferred from the claim text.