Parity Logging Overcoming The Small Write Problem In Redundant Disk Arrays
Parity Logging Overcoming The Small Write Problem In Redundant Disk Arrays
复制标题
DOI：
10.1145/165123.165143
复制
发表时间：
1993-05
期刊：
影响因子：
--
通讯作者：
Daniel Stodolsky;G. Gibson;M. Holland
中科院分区：
文献类型：
--
作者：
Daniel Stodolsky;G. Gibson;M. Holland
奇偶校验编码冗余磁盘阵列为读访问和大写访问提供了高可靠性、高性价比的二级存储。但是，它们在进行小的写操作时的性能要比镜像磁盘差得多，镜像磁盘是用于辅助存储的传统的、高度可靠的、但是昂贵的组织。不幸的是，在许多重要的、要求很高的应用程序（如在线事务处理）中，小的写操作占I/O工作负载的很大一部分。针对冗余磁盘阵列的小写入问题，提出了一种新颖的奇偶日志方法。奇偶性日志记录应用日志记录技术来大幅降低小写操作的成本。我们提供了奇偶记录和竞争方案（镜像、浮动存储和RAID级别5）的详细分析，并通过仿真验证了这些模型。奇偶校验日志提供了与镜像相媲美的性能，镜像是可选的单故障容忍度最好的磁盘阵列组织。但是，它的开销成本接近RAID级别5提供的最小值。最后，奇偶校验日志可以比所有三种替代方法更有效地利用数据缓存。
Parity encoded redundant disk arrays provide highly reliable, cost effective secondary storage with high performance for read accesses and large write accesses. Their performance on small writes, however, is much worse than mirrored disks—the traditional, highly reliable, but expensive organization for secondary storage. Unfortunately, small writes are a substantial portion of the I/O workload of many important, demanding applications such as on-line transaction processing. This paper presents parity logging, a novel solution to the small write problem for redundant disk arrays. Parity logging applies journalling techniques to substantially reduce the cost of small writes. We provide a detailed analysis of parity logging and competing schemes—mirroring, floating storage, and RAID level 5— and verify these models by simulation. Parity logging provides performance competitive with mirroring, the best of the alternative single failure tolerating disk array organizations. However, its overhead cost is close to the minimum offered by RAID level 5. Finally, parity logging can exploit data caching much more effectively than all three alternative approaches.