Design And Implementation Of The Adaptive Tiered Storage System

Applications need more and more storage space to store data,at the same time they require storage systems to provide better performance.For working out the conflict between the cost and the performance of storage systems,tiered storage systems have been adopted widely.Tiered storage systems that combine SSDs and HDDs mitigate the capital cost burden of SSDs,while benefiting from their superior I/O performance per unit cost.Though there are many tiered storage solutions available,they do not take the space of SSD into consideration sufficiently.The space of SSD can not be used fully when they do not migrate enough data on SSD or data migrated in and out of SSD constantly when they migrate too much data on SSD.This paper proposed an adaptive tiered storage system(ATS),which can regulate migrate threshold adaptively based on the data size of the workloads and the usage of the stroage devices.ATS can make full use the space of SSD,at the same time it prevent data from migrating in and out of SSD constantly.ATS realize this function via two key components.Initial Treshold Chooser(ITC)determines the initial threshold based on the part of the trace and the space of the available storage device.Adaptive Tier Processor(ATP)performs data migrating dynamically and threshold regulating adaptively once the system is running.ATP regulates threshold based on the data size of the workload and the usage of the storage device.ATP migrates hot data to SSD and cold on HDD dynamically.Our results show that ATS can get better average response time compared to ST(Static Threshold)and MOD(Migrate on Demand)no matter what circumstance it is under.ATS can reduce average response time by 53% compared to ST and 50% to MOD at most.