Performance Metrics for Erasure Codes in Storage Systems

Erasure codes that have good theoretical properties for a communication channel, need not have good properties for use in storage systems. Choosing the code Hamming distance to meet a desired reliability goal is only the first step in the erasure code selection process for a storage system. A storage system designer needs to carefully consider many other metrics that are specific to storage systems and their specific system configuration. In this article we first present one model of a storage system and then describe the metrics that are relevant in that model. We then outline a set of array codes that have been proposed for use in storage systems and compare and analyze them using our metrics. Our metrics assume a particular hardware architecture; however, the methodology can be easily adapted to other hardware models. Consequently, the principles described here can be modified by a storage system designer to fit his/her specific environment and so provide quantitative tools for array code comparison and selection criteria.

By: James Lee Hafner, Veera Deenadhayalan, Tapas Kanungo, KK Rao

Published in: RJ10321 in 2004


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