A Duplication-Aware SSD-Based Cache Architecture for Primary Storage in Virtualization Environment

Abstract

With the advantages of low latency, high performance, and low power consumption, solid state drives (SSDs) have been widely deployed as the cache layer between memory and back-end low-speed storage devices to narrow the performance gap between CPU and storage system. However, in virtualization environment, the high integration of virtual machines can introduce a lot of duplicate data blocks in the cache device. Existing cache architectures and replacement algorithms rarely take this situation into consideration. This greatly limits the efficient use of the cache device. For this case, we proposed a duplication-aware SSD-based cache architecture. In this architecture, duplicate data blocks can be significantly reduced, and the utilization efficiency of the cache device will be notably improved. Furthermore, to reduce the cache replacement overhead, we also proposed an improved adaptive replacement cache (ARC)-based replacement strategy, which we named D-ARC. Experiment results show that, in some situations, our cache architecture can improve the cache hit ratio by five times, reduce the average I/O latency by 63%, and eliminate SDD writes by 81%. Compared with the ARC-based replacement strategy, D-ARC can provide a performance improvement by about 16% if the configuration is set appropriately.