A 911 dispatch platform sizes etcd for HA. Why do operators typically choose an odd etcd member count?
Select an answer to reveal the explanation.
Short Explanation
Consensus is a majority vote—three or five judges beat a hung jury of four. Odd etcd member counts make “more than half” clean when someone drops offline. Even counts aren’t illegal, but they waste a seat without buying better failure tolerance.
Full Explanation
Raft-based etcd elects leaders and commits using majority quorum. Odd member counts (3, 5) maximize failure tolerance for a given size without adding a member that does not increase how many losses you can survive. Quorum math—not aesthetics—drives the odd-count convention.