Row-Diagonal Parity for Double Disk Failure Correction (Awarded Best Paper!)
نویسندگان
چکیده
Row-Diagonal Parity (RDP) is a new algorithm for protecting against double disk failures. It stores all data unencoded, and uses only exclusive-or operations to compute parity. RDP is provably optimal in computational complexity, both during construction and reconstruction. Like other algorithms, it is optimal in the amount of redundant information stored and accessed. RDP works within a single stripe of blocks of sizes normally used by file systems, databases and disk arrays. It can be utilized in a fixed (RAID-4) or rotated (RAID-5) parity placement style. It is possible to extend the algorithm to encompass multiple RAID-4 or RAID-5 disk arrays in a single RDP disk array. It is possible to add disks to an existing RDP array without recalculating parity or moving data. Implementation results show that RDP performance can be made nearly equal to single parity RAID-4 and RAID-5 performance.
منابع مشابه
Efficient parity placement schemes for tolerating up to two disk failures in disk arrays
In order to achieve high reliability in disk array systems, two new schemes using dual parity placement, called DH1 (diagonal±horizontal) and DH2 schemes, are presented. Both DH schemes can tolerate up to two disk failures by using two types of parity information placed in the diagonal and the horizontal directions, respectively, in a matrix of disk partitions. DH1 scheme can reduce the occurre...
متن کاملSPA: On-Line Availability Upgrades for Parity-based RAIDs through Supplementary Parity Augmentations
In this paper, we propose a simple but powerful on-line availability upgrade mechanism, Supplementary Parity Augmentations (SPA), to address the availability issue for parity-based RAID systems. The basic idea of SPA is to store and update the supplementary parity units on one or a few newly augmented spare disks for on-line RAID systems in the operational mode, thus achieving the goals of impr...
متن کاملVerification of Parity Data in Large Scale Storage Systems
Highly available storage uses replication and other redundant storage to recover from a component failure. If parity data calculated from an erasure correcting code is not updated or becomes otherwise corrupted, recovery from a failure does not recover the correct data but mostly garbled data. This paper presents an algebraic signature scheme that can detect parity discrepancies for parity calc...
متن کاملA Unified Form of EVENODD and RDP Codes and Their Efficient Decoding
Array codes have been widely employed in storage systems, such as Redundant Arrays of Inexpensive Disks (RAID). The row-diagonal parity (RDP) codes and EVENODD codes are two popular doubleparity array codes. As the capacity of hard disks increases, better fault tolerance by using array codes with three or more parity disks is needed. Although many extensions of RDP codes and EVENODD codes have ...
متن کاملOptimizing Cauchy Reed-Solomon Codes for Fault-Tolerant Storage Applications
In the past few years, all manner of storage systems, ranging from disk array systems to distributed and widearea systems, have started to grapple with the reality of tolerating multiple simultaneous failures of storage nodes. Unlike the single failure case, which is optimally handled with RAID Level-5 parity, the multiple failure case is more difficult because optimal general purpose strategie...
متن کامل