Impact of stripe unit size on performance and endurance of SSD-based RAID arrays

Over the past decades, Redundant Array of Independent Disks (RAIDs) have been congured based on mechanical characteristics of Hard Disk Drives (HDDs). With the advent of Solid-State Drives (SSDs), congurations such as stripe unit size can be far from the characteristics of SSDs. In this paper, we investigate the eect of stripe unit size on the endurance and the overall I/O performance of an SSD-based RAID array and compare the optimal stripe unit size with the suggested stripe unit sizes for HDD-based RAID. To this end, we rst examine the number of extra page reads and writes imposed by write requests, and then observe the corresponding impact on the overall throughput and the average response time of SSD-based RAID arrays. The eect of extra page writes for dierent stripe unit sizes and their impact on endurance has been also examined. To validate the analytical study, we have used I/O intensive traces and simulated an SSD-based RAID array, using DiskSim simulator with dierent stripe unit sizes. The experimental results reveal that unlike HDD-based RAID arrays, a 4 KB stripe unit size can signicantly improve the throughput, response time and endurance of an SSD-based RAID4 array (up to 67.6%, 52.2%, and 48.6%, respectively), as compared to 128 KB stripe unit size.