Paxos and Raft

Basic Paxos

Paxos is a family of consensus algorithms that work in a distributed system. The Paxos algorithm was developed by Leslie Lamport and published in his 1998 paper, “The Part-Time Parliament.”

The host proposing a value is a proposer and the host accepting the proposal is an acceptor. Basic Paxos is the most basic consensus algorithm of the Paxos family. Basic Paxos has two phases, Phase 1 and Phase 2.

Phase 1

Phase 1 also has two subphases:

• Prepare

• Promise

In the prepare phase, the proposer creates a Prepare message with a number X, which is a unique identifier of the message and greater than any of the previous Prepare messages from that proposer. Now, the proposer sends this message to a Quorum of acceptor hosts.

Once the acceptor receives the message, there are two scenarios:

• If ...