Is it supported to modify the control plane node size in a running OpenShift Container Platform 4.x cluster?
Environment
- Red Hat OpenShift Container Platform (RHOCP) 4.6 or later
Issue
- Is masters (control plane) resizing a supported day-2 operation?
- How more resources can be added to the master nodes without reinstalling the cluster?
Resolution
- Refer to the article How to resize nodes in OCP 4.6 or later for AWS or Azure for a step-by-step.
- Refer to the article How to increase memory resource for worker nodes in OCP 4 for VMware for increasing memory resources for a VMWare OpenShift cluster.
- Alternatively, in installer-provisioned infrastructure (IPI) clusters where this is supported, Control Plane Machine Sets can be used for this purpose.
At the time when this article is being written (current major latest version: 4.8), a rolling update resizing for the master nodes (shut down one of the master nodes, modify its memory and/or CPU and start up again) is possible if your infrastructure allows it.
Cautions:
- Make sure that the rest of the masters are completely healthy before removing or shutting down one of them.
- Removing or shutting down a master may be a risky operation in an overloaded or unhealthy cluster. You can open a support case if your cluster is in this situation, you have to increase the hardware of your master nodes and you need some guidance.
Looking forward:
- A Request For Enhancement(RFE) has been created so that this rolling update procedure is supported on any kind of Infrastructure. Ask Red Hat Support if you need to know more about the status of that RFE.
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