Research

MySQL is the most popular transactional datastore deployed at Meta with a storage footprint in the order of petabytes. Over the years, several components have undergone significant changes to meet the demands posed by production workloads. One such effort was to redesign the replication protocol to use a modified version of Raft instead of traditional semisynchronous replication.

Even though Raft was a good fit for our requirements, the original algorithm did not offer much flexibility in choosing quorums which is important for latency sensitive applications. In this paper, we describe our changes to the original Raft algorithm required for supporting flexible data commit quorums. We discuss the impact of these changes on workload performance, fault tolerance and ease of integration into the existing production setup.