Empirical study of redo and undo logging in persistent memory

Atomic and durable transactions are widely used to ensure the crash consistency in persistent memory (PM). However, whether to use redo or undo logging is still a hotly debated topic in persistent memory systems. In this paper, we empirically study the performance of both redo and undo logging using NVML, a persistent memory transactional object store framework. Our results on an NVDIMM server show that redo logging significantly outperforms undo logging for workloads in which a transaction updates large number of different objects, while it underperforms undo logging for workloads with intensive read operations. Furthermore, undo logging is more sensitive to the read-to-write ratios, compared to redo logging. Finally, our experiments also demonstrate that asynchronous log truncation is much helpful in redo logging for log-heavy transactions.