Caching strategies for high-performance storage media

Due to the large access latency of hard disks during data retrieval in computer systems, buffer caching mechanisms have been studied extensively in database and operating systems. By storing requested data into the buffer cache, subsequent requests can be directly serviced without accessing slow disk storage. Meanwhile, high-speed storage media like PCM (phase-change memory) have emerged recently, and one may wonder if the traditional buffer cache will be still effective for these high-speed storage media. This article answers the question by showing that the buffer cache is still effective in such environments due to the software overhead and the bimodal data access characteristics. Based on this observation, we present a new buffer cache management scheme appropriately designed for the system where the speed gap between cache and storage is narrow. To this end, we analyze the condition that caching will be effective and find the characteristics of access patterns that can be exploited in managing buffer cache for high performance storage like PCM.