Error detection/correction and fault detection/recovery – Pulse or data error handling – Digital data error correction
Reexamination Certificate
1998-05-13
2001-06-12
Moise, Emmanuel L. (Department: 2133)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Digital data error correction
C714S006130, C714S766000, C714S800000
Reexamination Certificate
active
06247157
ABSTRACT:
BACKGROUND
1. Field
The invention is related to encoding data signals and, more particularly, to encoding data signals for storage.
2. Background Information
As is well-known, it is common, in connection with the operation of a personal computer (PC) or other computer, to store data signals in a secondary memory or storage medium, such as a hard drive, disk or disk array, for example. Redundant disk arrays may be used to build highly available and reliable disk subsystems. Typically, the data signals are “exclusive-ORed” from some number of disks and maintained on a redundant disk and, in the event of a disk failure, the data signals on the failed disk are reconstructed using the data on surviving disks and writing this into a spare disk. However, data signals may also be lost if a second disk fails before the reconstruction is complete. Unfortunately, traditional disk arrays typically are inadequate for protecting from the loss of more than one disk. Therefore, a technique that will not lose data signals even when multiple disks fail and that, likewise, exhibits efficient performance is desirable.
SUMMARY
Briefly, in accordance with one embodiment of the invention, a method of encoding data signals for storage to tolerate failure of a storage unit of a storage medium includes the following.
For N+2 storage units, N being a positive integer, each of the storage units being divided into N storage blocks, 2N blocks of priority signals are produced from (N)(N) blocks of data signals. The N(N+2) blocks of parity and data signals are allocated over the N+2 storage units of the storage medium so that the 2N blocks of parity signals are not exclusively stored in two of the N+2 storage units.
Briefly, in accordance with another embodiment of the invention, a storage medium includes: N+2 storage units to store binary digital signals, N being a positive integer, each of the storage units being divided into N storage blocks, the N+2 storage units having stored thereon 2N blocks of parity signals and (N)(N) blocks of data signals, the 2N blocks of parity signals being based upon the (N)(N) blocks of data signals. The 2N blocks of parity signals are distributively stored over the N+2 storage units so that the 2N blocks of parity signals are not exclusively stored in two of the N+2 storage units.
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Intel Corporation
Moise Emmanuel L.
Seddon Kenneth
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