This is the documentation for etcd2 releases. Read etcd3 doc for etcd3 releases.


This document defines the various terms used in etcd documentation, command line and source code.


Node is an instance of raft state machine.

It has a unique identification, and records other nodes' progress internally when it is the leader.


Member is an instance of etcd. It hosts a node, and provides service to clients.


Cluster consists of several members.

The node in each member follows raft consensus protocol to replicate logs. Cluster receives proposals from members, commits them and apply to local store.


Peer is another member of the same cluster.


A proposal is a request (for example a write request, a configuration change request) that needs to go through raft protocol.


Client is a caller of the cluster's HTTP API.

Machine (deprecated)

The alternative of Member in etcd before 2.0