面向安全持久性内存的元数据协同管理方法

Coordinated Metadata Management for Secure Persistent Memory

新型非易失存储器是下一代计算机内存最具潜力的候选之一.基于非易失存储器构建持久性内存系统面临着2方面挑战:保证数据安全性、优化写操作.为此,现有工作提出加密和完整性检测技术以保证安全性,同时提出选择重加密策略以优化写操作.这些技术在持久性内存中引入多种元数据,但尚无研究工作综合考虑各类元数据特性以实现高效管理.为解决此问题,提出一种面向安全持久性内存的元数据协同管理方法(coordinated metadata management for secure persistent memory,COTANA).COTANA将加密和选择重加密元数据整合在相同块中,以减少加解密时元数据访问开销.同时,COTANA将整合后的块作为叶子结点构建完整性检测树,并通过将消息鉴别码放置在纠错码芯片中避免额外访问延迟.此外,通过实验发现数据块中不同字节存在不同修改频率.在选择重加密时,COTANA采用动态数据分片策略,从现有的连续分片方法和针对修改频率规律设计的聚集分片方法中动态选择造成位翻转最少的方法.实验结果显示,与采用最新的元数据管理方法和选择重加密策略的系统相比,COTANA最多能提升13.7%的性能,并减少21.3%的位翻转.

Non-volatile memory(NVM)is an emerging candidate for the next generation of main memory.Building persistent memory systems with NVM faces two challenges,including ensuring data security and optimizing write operations.Recent studies have proposed encryption and integrity verification techniques to protect in-memory data,and have proposed selective reencryption techniques to reduce write overhead.These techniques introduce various metadata that are stored in persistent memory.However,existing metadata management mechanisms only consider part of the metadata,which still causes significant metadata access overhead.To address the problem,we propose COTANA,a coordinated metadata management method for secure persistent memory.COTANA places the encryption and the selective reencryption metadata in the same metadata blocks,so that fetching the metadata for encryption/decryption needs only one read.COTANA builds an integrity tree on these metadata blocks,and places the message authentication codes(MAC)in an ECC chip to avoid extra access latency.Moreover,we observe that the bytes within a block have different modification frequencies for real-world workloads.Therefore,for selective reencryption,COTANA adopts a dynamic data partition scheme that dynamically chooses the partition methods with lowest bit flips.The methods include an existing successive partition method and a gathered partition method that is designed based on the modification frequencies.The evaluation results show that COTANA improves performance by up to 13.7%,and decreases bit flips by up to 21.3%compared with the state-of-the-art designs.