https://rancher.com/ logo
Title
n

nutritious-vase-53845

03/01/2023, 11:42 AM
Hi all, I have two machines and both are configured seperately (with k3s) as masters. Now I need to combine these two into one cluster, having both as masters (for high availability). Is this possible and can you please explain the steps to achive this. Thanks Pai
r

rough-farmer-49135

03/01/2023, 2:33 PM
I'm not certain, but my gut guess is that you have to remove k3s from one of them and then join it to the other's cluster, though if you are using the internal etcd then you'll have to add a third master for things to work (if you're using an external database instead then two masters will be ok).
c

creamy-pencil-82913

03/01/2023, 4:20 PM
You need an odd number of servers for HA with embedded etcd. Two servers is not a supported number, due to quorum requirements.
n

nutritious-vase-53845

03/01/2023, 4:50 PM
@rough-farmer-49135 you mean by removing k3s,is to uninstall k3s.
@creamy-pencil-82913 I did see that for HA to work 3 servers are needed bcoz of quorum requirements. We are planning for that too.
r

rough-farmer-49135

03/01/2023, 4:51 PM
Yep. I don't think you can join one existing cluster to another, but if you fully uninstall from the node there's no reason you couldn't join to the existing node's cluster.
I could be wrong about that, but if I were I suspect Brad would've corrected me when he pointed out quorum.
n

nutritious-vase-53845

03/01/2023, 4:54 PM
From HA perspective, we will add one more new server, but having the running cluster making it part of another cluster was my main challenge.
c

creamy-pencil-82913

03/01/2023, 5:04 PM
you can’t merge the clusters. On the nodes that you want to join to the other cluster, you should uninstall, and then join them to the other cluster. Treat it as if you’re starting from scratch. Anything you had deployed to the cluster you eliminated will need to be manually migrated over.
n

nutritious-vase-53845

03/01/2023, 5:06 PM
Got it. Thank you @rough-farmer-49135 @creamy-pencil-82913