Compensatory Caching Algorithm For Magnetoelectric Hybrid Storage

Buffer cache is one of the key components of the computer system, which can use the access locality to promote the I/O performance. The traditional cache replacement algorithms only use the miss rate as the evaluation standard. They ignore the features of the lower storage devices, and consider the miss cost the same. However, in Hybrid Storage System which consists of solid state drive and hard disk drive, the solid state drive's performance is different from the disk's, that leads to the punishment of the miss in two kind of medium is not the same.In hybrid storage system, due to different storage medium which has different I/O latency, this paper proposes a new compensatory cache replacement algorithm named C-cache to improve the read performance. The key idea of the C-cache is to give more read cache space to the data on hard disk, which can reduce the read request send to the hard disk. Because of the high punishment of the missing read on hard disk is reduced, the total punishment of the missing read in the whole system is reduced too. So the average response time of the whole read request is shorter than before, the user's Quality of Service can be increased. In order to verify the validity of the C-cache, we designe and implemente the C-cache based on LRU replacement algorithm, and analyse the factors which can influence the effectiveness of C-cache based on the experimental results.The simulation experiments show that compared with classic LRU algorithm, using C-cache can reduce up to 50% of the average response time of read request.