A Page-Based Storage Framework for Phase Change Memory

Phase change memory (PCM) has emerged as a promising candidate for next-generation memories, owing to its low power consumption, non-volatility, and high storage-density. However, PCM has limited write endurance, i.e., it can only undergo a limited number of write operations, leading to a short lifecycle. Thus, it is an important issue to find out an efficient way to use PCM in memory hierarchy, so that we can take advantage of the merits of PCM and prolong its lifecycle. Although PCM can support byte accesses, currently it has to work on top of pagebased HDDs or SSDs. Therefore, a feasible way is to use PCM as a page buffer in memory hierarchy. Based on this assumption, in this paper we propose an efficient page-based storage scheme for PCM. We propose to use both DRAM and PCM as page buffers, forming a hybrid page buffer for DBMSs. Particularly, we develop three new techniques for PCM storage management. First, we propose a dual-bucket list to organize PCM spaces. Second, we use a small DRAM cache managed by an age-based policy to cache writes to PCM pages. Third, we propose a new page allocation algorithm that considers both page migration and page swapping to reduce the writes to PCM. We conduct extensive experiments on a simulated PCM-based storage system over both synthetic and realistic traces. The results suggest the effectiveness of our proposal. KeywordsPhase change memory; Storage management; Buffer management; Page migration