KodeKloud Notes

In this lesson, we’ll explore the distinct roles of voting and non-voting members in a Consul cluster. By default, server nodes participate in Raft’s leader election and maintain quorum. However, if you need additional read capacity without impacting election stability, add non-voting members. These nodes replicate the same data but are excluded from voting, boosting read throughput while preserving the Raft quorum.

Comparison Table

Member Type	Votes in Raft Election	Data Replication	Primary Use Case
Voting Member	Yes	Yes	Ensures quorum, leader election, high availability
Non-voting Member	No	Yes	Scales reads, redundancy zones, workload isolation

Note

Use non-voting members to horizontally scale read operations in high-traffic environments without the risk of quorum changes.

Configuring a Non-voting Member

You can designate a node as non-voting in two ways:

In the agent’s configuration file (consul.hcl):
```
# consul.hcl
non_voting = true
```
Via the command line when starting the agent:
```
consul agent ... --non-voting-member
```

Warning

Be cautious not to overload your cluster with too many non-voting members, as excessive replication traffic can impact network resources.

Example: Verifying Peers

Start with a three-node cluster where all servers are voters. List the Raft peers:

$ consul operator raft list-peers
Node           ID               Address            State     Voter  RaftProtocol
Consul-Node-A  10.0.10.51:8300  10.0.10.51:8300    follower  true   2
Consul-Node-B  10.0.11.23:8300  10.0.11.23:8300    leader    true   3
Consul-Node-C  10.0.10.3:8300   10.0.10.3:8300     follower  true   2

Next, add a fourth node configured as a non-voting member. Re-run the command to see the updated list:

$ consul operator raft list-peers
Node           ID               Address            State     Voter   RaftProtocol
Consul-Node-A  10.0.10.51:8300  10.0.10.51:8300    follower  true    2
Consul-Node-B  10.0.11.23:8300  10.0.11.23:8300    leader    true    3
Consul-Node-C  10.0.10.3:8300   10.0.10.3:8300     follower  true    2
Consul-Node-D  10.0.11.62:8300  10.0.11.62:8300    follower  false   2

Here, Consul-Node-D synchronizes all data without voting, providing extra read capacity while keeping the existing quorum intact.

References

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