Reliability Evaluation of Erasure-coded Storage Systems with Latent Errors

IF 2.1 3区计算机科学 Q3 COMPUTER SCIENCE, HARDWARE & ARCHITECTURE

ACM Transactions on Storage Pub Date : 2022-11-19 DOI:10.1145/3568313

I. Iliadis

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引用次数: 0

Abstract

Large-scale storage systems employ erasure-coding redundancy schemes to protect against device failures. The adverse effect of latent sector errors on the Mean Time to Data Loss (MTTDL) and the Expected Annual Fraction of Data Loss (EAFDL) reliability metrics is evaluated. A theoretical model capturing the effect of latent errors and device failures is developed, and closed-form expressions for the metrics of interest are derived. The MTTDL and EAFDL of erasure-coded systems are obtained analytically for (i) the entire range of bit error rates; (ii) the symmetric, clustered, and declustered data placement schemes; and (iii) arbitrary device failure and rebuild time distributions under network rebuild bandwidth constraints. The range of error rates that deteriorate system reliability is derived analytically. For realistic values of sector error rates, the results obtained demonstrate that MTTDL degrades, whereas, for moderate erasure codes, EAFDL remains practically unaffected. It is demonstrated that, in the range of typical sector error rates and for very powerful erasure codes, EAFDL degrades as well. It is also shown that the declustered data placement scheme offers superior reliability.

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具有潜在错误的擦除编码存储系统的可靠性评估

大规模存储系统采用擦除编码冗余方案来防止设备故障。评估潜在扇区错误对平均数据丢失时间（MTTDL）和预期年数据丢失率（EAFDL）可靠性指标的不利影响。建立了一个捕捉潜在误差和设备故障影响的理论模型，并推导了感兴趣的度量的闭合表达式。擦除编码系统的MTTDL和EAFDL是针对（i）比特错误率的整个范围解析地获得的；（ii）对称、集群和去集群的数据放置方案；以及（iii）在网络重建带宽约束下的任意设备故障和重建时间分布。分析推导了降低系统可靠性的误差率范围。对于扇区错误率的实际值，所获得的结果表明MTTDL退化，而对于中等擦除码，EAFDL实际上保持不受影响。研究表明，在典型的扇区错误率范围内，对于非常强大的擦除码，EAFDL也会降级。还表明，去簇数据放置方案提供了优越的可靠性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

ACM Transactions on Storage COMPUTER SCIENCE, HARDWARE & ARCHITECTURE-COMPUTER SCIENCE, SOFTWARE ENGINEERING

CiteScore

4.20

自引率

5.90%

发文量

审稿时长

>12 weeks

期刊介绍： The ACM Transactions on Storage (TOS) is a new journal with an intent to publish original archival papers in the area of storage and closely related disciplines. Articles that appear in TOS will tend either to present new techniques and concepts or to report novel experiences and experiments with practical systems. Storage is a broad and multidisciplinary area that comprises of network protocols, resource management, data backup, replication, recovery, devices, security, and theory of data coding, densities, and low-power. Potential synergies among these fields are expected to open up new research directions.