| Along with the development of manufacturing process of semiconductor, the size of DRAMand Flash Memory is getting smaller and smaller. However, memory scaling is in jeopardy ascharge storage and sensing mechanisms become less reliable for prevalent memory technologies,such as DRAM and Flash Memory. Under this circumstance, there is no time to delay to researchand develop ideal semiconductor memory to solve this problem. Thus, Phase Change Memory(PCM), a new generation of memory with high density, high speed and long-life, is developed.PCM is a new resistance-type nonvolatile semiconductor memory, having the advantages ofboth RAM and Flash Memory. However, PCM cells can endure only a maximum of107-108writes,making a PCM based system have a lifetime of merely several years under ideal conditions. If onePCM cell is uninterruptedly written, it may lose efficacy in several seconds. Therefore, we proposea strategy to make PCM based system work longer.After analyzing existing storage management strategy for Flash Memory and PCM, we comeup with Exchange-Wear-Leveling, which is easily completed on hardware and has low memoryconsumption. Then, we introduce a hybrid hardware architecture which consists of PCM andNAND Flash; analyze the structure of data storage between file system and external memorysystem; separate the metadata and user data which are respectively stored in PCM and NANDFlash. In this paper, we focus on the management strategy for PCM with metadata. The main ideais to partition the memory into multi-area and multi-array for data striping. We balance the writingoperations during the whole system by exchanging adjacent line within a memory array andexchanging hot data-area and cold data-area.Comparing with existing algorithms, our solution can make the address-mapping morediscrete and restrain from repeatedly writing on the same cell, so as to lengthen the lifetime ofmemory system and usability. Finally, we prove the performance superiority of this algorithm bysimulation. |
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