Replica Distribution Policy

[MrPleom-sirius]

General Question
If there are three nodes, each node has three pods (stored), and the RF is set to 3, if a node goes down, may all three replicas of a partition be lost? In other words, will the operator distribute different replicas of the same partition on different nodes instead of just on different pods?

[MrPleom-sirius]

I would appreciate your reply. Thanks.

[egasimov]

Hi.

• RF doesn’t guarantee safety by itself. NebulaGraph will try to keep three replicas, but it doesn’t know whether those replicas are all on the same Kubernetes node unless you explicitly tell Kubernetes how to spread them.
• If all 3 replicas land on the same node and that node dies, you can lose that partition even with RF=3.
• To avoid that, add pod anti-affinity / spread constraints so Kubernetes schedules storage pods across distinct nodes.
• For even stronger guarantees, use Zones in enterprise mode — which NebulaGraph itself understands and respects when distributing replicas.