Data Consistency Protocol Research Articles

Data consistency protocol for multicloud systems

Data consistency protocol for multicloud systems

Data consistency protocol for multicloud systems

Data consistency protocol for multicloud systems

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.

A Fast Evaluation Approach of Data Consistency Protocols within a Compilation Toolchain

Shared memory is a critical issue for large distributed systems. Despite several data consistency protocols have been proposed, the selection of the protocol that best suits to the application requirements and system constraints remains a challenge. The development of multi-consistency systems, where different protocols can be deployed during runtime, appears to be an interesting alternative. In order to explore the design space of the consistency protocols a fast and accurate method should be used. In this work we rely on a compilation toolchain that transparently handles data consistency decisions for a multi-protocol platform. We focus on the analytical evaluation of the consistency configuration that stands within the optimization loop. We propose to use a TLM NoC simulator to get feedback on expected network contentions. We evaluate the approach using five workloads and three different data consistency protocols. As a result, we are able to obtain a fast and accurate evaluation of the different consistency alternatives.

LND

The expensive overhead of synchronous I/O has now become the bottleneck of increasing efficiency of data storage in transaction-based systems. This paper proposes a multi-tier storage device, the LND (Local-Network Ram- Disk) device, which uses idle memories and disks in NOW (Network of Workstations) as persistent repositories so that access latency is transformed from magnetic disk seek-and-transfer latency to the sum of network transfer latency, memory write latency, and asynchronous I/O latency. Two fast data consistency protocols based on multicast technique are also introduced to improve performance without sacrificing reliability. Experimental results show that the LND device is one order of magnitude faster than traditional disks in synchronous I/O performance. Moreover, a fault tolerant recovery algorithm is proposed to protect the system from various kinds of failures and to facilitate quick recovery from crashes.