ACS: an alternate coding scheme to improve degrade read performance for SSD-based RAID5 systems. (20th November 2021)

• Record Type: Journal Article
• Authors: Pan, Yubiao; Lin, Mingwei
• Is Part Of: International journal of high performance systems architecture. Volume 10:Number 2(2021)
• Page Start: 70
• Page End: 79
• Publication Date: 2021-11-20
• Subjects: SSDs -- solid-state drives -- RAID -- degraded read -- disk I/Os -- performance -- storage system -- coding -- system architecture; Computer architecture -- Periodicals; Computer systems -- Periodicals; High performance computing -- Periodicals; 004.205
• Languages: English
• ISSNs: 1751-6528

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.