Distributed Data Persistency

Distributed applications such as key-value stores and databases provide fault tolerance by replicating records in the memories of different nodes, and using data consistency protocols to ensure consistency across replicas. In this environment, nonvolatile memory (NVM) offers the ability to attain high-performance data durability. However, it is unclear how to tie NVM memory persistency models to the existing data consistency frameworks. In this article, we propose the concept of distributed data persistency (DDP) model, which is the binding of the memory persistency model with the data consistency model in a distributed system. We reason about the interaction between consistency and persistency by using the concepts of visibility point and durability point. We design low-latency distributed protocols for several DDP models, and investigate the tradeoffs between performance, durability, and intuition provided to the programmer.