FusionCache:采用闪存的iSCSI存储端融合缓存机制

发布时间：2018-01-09 00:12

本文关键词：FusionCache:采用闪存的iSCSI存储端融合缓存机制　出处：《哈尔滨工业大学学报》2017年11期 　论文类型：期刊论文

【摘要】：针对原生的iSCSI目标端控制器缺乏独立的缓存模块问题,为了进一步提高存储区域网的整体性能,在iSCSI target软件中引入了一种基于闪存的融合缓存机制FusionCache.FusionCache利用闪存和DRAM组成统一的融合缓存架构,闪存充当DRAM的扩展空间,DRAM分为缓存块元数据区和前端缓存区.元数据区基于基数树管理缓存块元数据,用于加速缓存块的查找;前端缓存区基于回归拟合统计并预测缓存块访问热度,并吸收大量写入对闪存带来的冲击,只允许热点数据进入闪存.FusionCache采用改进的LRU算法对缓存块进行替换,并且在写回过程中考虑iSCSI会话状态.实验结果表明:FusionCache能降低对后端磁盘设备的访问频率,提高I/O响应的速度和吞吐.与只采用DRAM的缓存机制以及原生iSCSI target相比,FusionCache的I/O访问延时分别降低了33%和60%,吞吐分别提高了25%和54%;相较于Facebook提出的Flashcache机制,FusionCache的吞吐性能提高了18%,延时降低了27%;FusionCache还具有良好的读缓存命中率;此外,FusionCache能够减少闪存的写入次数,提高闪存使用寿命.FusionCache提供良好的网络存储效率,并且降低了使用成本.
[Abstract]:According to the iSCSI target controller lack native cache module problems independently, in order to further improve the overall performance of the storage area network, in the iSCSI target software introduced a fusion caching architecture FusionCache.FusionCache fusion caching mechanism using flash flash and DRAM flash based on the unified, as extended space DRAM, DRAM is divided into metadata cache block area and the front buffer. The metadata cache block area base tree management based on metadata, to speed up the cache block lookup; front-end buffer cache block and statistical regression prediction based on visit and absorb a lot of heat, write to flash the impact, allowing only the hot data into the flash.FusionCache using the improved LRU algorithm for cache block replace, and write back in the iSCSI session state in the process of consideration. The experimental results show that FusionCache can reduce the back-end disk The frequency of access to the device, improve I/O response speed and throughput. Compared with only using caching mechanisms of DRAM and native iSCSI target, FusionCache I/O access delay is decreased by 33% and 60%, the throughput increased respectively by 25% and 54%; compared to the Flashcache mechanism proposed by Facebook, FusionCache throughput performance is improved by 18%, reduce the delay 27%; FusionCache also has a good read cache hit rate; in addition, the FusionCache can reduce the number of write flash memory, improve the service life of flash memory.FusionCache network to provide good storage efficiency, and reduce the cost.

【作者单位】：中国科学院声学研究所国家网络新媒体工程技术研究中心;中国科学院大学;
【基金】：中国科学院战略性先导科技专项课题(XDA06010302) 中科院创新研究院前瞻项目(Y555021601)
【分类号】：TP333
【正文快照】： 近年来存储介质技术的进步和个人云存储业务的迅速发展,使得网络存储系统再次成为学术界和工业界研究的热点,存储区域网(Storage AreaNetwork,SAN)是解决数据密集型应用I/O性能瓶颈的重要手段,其中IP SAN采用i SCSI[1]协议.在云计算和大数据时代,海量的网络数据尤其是视频流量

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