面向非易失存储器外存系统的缓存机制

New Caching Strategy for Storage System Based on Non-volatile Memory

非易失存储器具有接近于DRAM的访问速度,是构建高性能外存系统和提高大数据系统性能的重要手段,但非易失存储器存在写次数有限和写能耗较高等问题.本文引入缓存技术,使用写缓存合并对同一数据的多次写操作,减少对非易失存储器的写次数;使用原始缓存减少写回非易失存储器的数据量;设计了写缓存混合粒度管理算法、双缓存协调算法和缓存空间协调策略,减少了非易失存储器的写数据量,增加外存系统的使用寿命,降低了外存系统能耗,提高了I/O性能.最后在开源基于对象存储设备Open-osd上,实现了面向非易失存储器外存系统缓存机制的原型,使用存储系统通用测试工具Filebench和Postmark、以及多个通用数据集进行了测试与分析,验证了面向非易失存储器外存系统缓存机制能减少21%-77%的外存写数据量,提高了8%-37%的I/O性能,检验了面向非易失存储器外存系统缓存机制的有效性.

Non-volatile memory is close to the DRAM＇ s access speed. It is a very significant way in building high performance storage system and also improves the performance of large data system. Nonetheless, the non-volatile memory has limited write endurance and the problem of high writing energy consumption. We introduce the cache technology. The write cache is used to avoid writing the same data repeatedly and hence reduce the amount of writing non-volatile memory data. The original cache is used to reduce the amount of data being written back to the non-volatile memory. We have designed the write cache management algorithm of hybrid granularity; a cache coordination algorithms and cache space coordination strategy, thus reducing the data quantity of writing non-volatile memory, increasing service life of storage system,reducing the energy consumption,and improving the I/O performance of disk systems. Finally ,in the open source Object-based Storage Device Open-osd,we implemented the non-volatile cache memory storage system prototype. We used File bench and postmark,the universal test tool for storage system,to test our prototype. A lot of common data sets were tested and analyzed, we verified the non-volatile cache memory storage system to see, it could reduce 21%-77% amount of writing back data, and improve 8%-37% of system I/O performance,it was verified that,the non-volatile memory storage system cache mechanism was very effective.