面向非易失内存的数据一致性研究综述

A Survey of Data Consistency Research for Non-Volatile Memory

随着DRAM技术面临密度扩展瓶颈以及高泄漏功耗问题,新型非易失内存(non-volatile memory,NVM)因其非易失、高密度、字节寻址和低静态功耗等特性,已经得到学术界和工业界的广泛关注.新型非易失内存如相变内存(phase change memory,PCM)很可能替代DRAM或与DRAM混合作为系统主内存.然而,由于NVM的非易失特性,存储在NVM的数据在面临系统故障时可能由于部分更新或内存控制器写重排序而产生不一致性的问题.为了保证NVM中数据的一致性,确保对NVM写操作的顺序化和持久化是基本要求.NVM有着内在缺陷如有限的写耐久性以及较高的写延迟,在保证NVM数据一致性的前提下,减少NVM写次数有助于延长NVM的寿命并提高NVM系统的性能.重点讨论了基于NVM构建的持久索引、文件系统以及持久性事务等数据一致性研究,以便为实现低开销的数据一致性提供更好的解决方案或思路.最后给出了基于NVM的数据一致性研究展望.

As DRAM technology is facing the bottleneck in density scaling and the problem of high power leakage,novel non-volatile memory(NVM)has drawn extensive attention from academia and industry,due to its superiority in non-volatility,high-density,byte addressability,and low static power consumption.Novel non-volatile memory such as phase change memory(PCM)is likely to substitute or complement DRAM as system main memory.However,due to the non-volatility of NVM,when system failed,data stored in NVM may be inconsistent by reason of partial updates or memory controller write reordering.In order to guarantee the consistency of data in NVM,it is essential to ensure the serialization and persistence in NVM write operations.NVM has inherent drawbacks,such as limited write endurance and high write latency,thus reducing the number of writes can help prolong the lifetime of NVM and improve the performance of NVM-based systems as long as data consistency in NVM is guaranteed.This paper focuses on data consistency based on NVM,especially on persistent indexes,file systems and persistent transactions,and to provide better solutions or ideas for achieving low data consistency overhead.Finally,the possible research directions of data consistency based on NVM are pointed out.