Title: ACS: an alternate coding scheme to improve degrade read performance for SSD-based RAID5 systems

Authors: Yubiao Pan; Mingwei Lin

Addresses: School of Computer Science and Technology, Huaqiao University, Xiamen, 361021, China ' College of Mathematics and Informatics, Fujian Normal University, Fuzhou, 350007, China

Abstract: To guarantee high performance and reliability, storage systems require better devices and data redundancy schemes, e.g., SSD-based RAID5. However, failures in the large-scale storage systems are common. In order to serve requests on a failed node, the SSD-based RAID5 causes additional disk I/Os to trigger degraded reads. Existing coding methods are not suitable for the SSD-based RAID5. How to maintain the same storage cost as the traditional RAID5 does while obtaining less disk I/Os for degraded reads is an interesting problem. In this paper, we first come up with an alternate coding scheme (ACS) by using the characteristics of SSD to reduce disk I/Os for boosting degraded reads. To work for realistic workloads, we further propose ACS-W and ACS-DR approaches for write and degraded requests. Our evaluations based on the trace-driven simulator with real-world workloads show that ACS indeed reduces disk I/Os and improves the degraded read performance.

Keywords: SSDs; solid-state drives; RAID; degraded read; disk I/Os; performance; storage system; coding; system architecture.

DOI: 10.1504/IJHPSA.2021.119149

International Journal of High Performance Systems Architecture, 2021 Vol.10 No.2, pp.70 - 79

Received: 16 Jan 2021
Accepted: 16 Mar 2021
Published online: 25 Nov 2021 *

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