RKE HA understanding

Hello Rancher’s,

We want to create an cluster via RKE with 9 Nodes.
Is it better to give all 9 Nodes “worker, etcd, controlplane” ? Or should we give the 9 nodes only “worker” role and install 3 additional nodes with “etcd and controlplane” ? Can the cluster work with only 1 etcd and controlplane if 2 nodes go offline.

We need the lowest downtime.
Whats the best practis?

Best Reagrds

You need a strict majority (more than half, not exactly half ) of etcd nodes available for the cluster to work. So you an odd number of them… 3 etcd can survive the failure of 1 node. 5 -> 2 nodes.

For control plane there just needs to be one or more available.

You can have multiple roles on a single node, this is relatively common for small clusters. So 3 nodes with all 3 roles each works.

The next step up is typically 3-5 etcd+control nodes separate from workers, which has some security and performance benefit.

Then etcd and control each on their own separate sets of nodes, typically for large clusters, which has some more security and performance benefit.

1 Like

Hello Vincent,

Thank you for your respone.
Can you confirm my config:

9 Nodes: all have the worker’s role -> 3 of them have the etcd role and 3 have the controlplane role.
If i lose 2 Nodes that includes the etcd role the cluster isn’t working. So i had to go up to 5 etcd to beat the failure of 2 nodes with etcd.

Best regards