Module openraft::docs::cluster_control

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§Managing Clusters: Adding/Removing Nodes

The Raft type offers various API methods to control a raft cluster. Several concepts are associated with cluster management:

  • Voter: A raft node responsible for voting, electing itself as a Candidate, and becoming a Leader or Follower.

  • Candidate: A node attempting to elect itself as the Leader.

  • Leader: The sole node in a cluster that handles application requests.

  • Follower: A node that acknowledges the presence of a valid leader and only receives replicated logs.

  • Learner: A node that cannot vote but only receives logs.

Voter state transition:

                         vote granted by a quorum
          .--> Candidate ----------------------> Leader
heartbeat |     |                                  |
timeout   |     | seen a higher Leader             | seen a higher Leader
          |     v                                  |
          '----Follower <--------------------------'

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