Required # of vCPUS/Clusters

Question

Hi.

I am trying to get wiser about vCPUS. Recently we created a new AKS cluster, and we tried to run it empty, i.e. without any services. Then some of our services on the old cluster stopped due to memory shortages. After some checks, it turned out that we had reached the limit on the vCPUS. (red line). I requested an increase in vCPUS which were given. But before we start the new Cluster (we want to split Production from Test), I am wondering about how to calculate or understand the required quota for vCPUs. I have tried to search the net, but I cannot see any obvious connection between resources and vCPUS. Any possibility to shed some light on this?

Answer 1

Hello, @Bernt Rosmo !

How do I calculate vCPU quota requirements for my AKS cluster?
This is an important architecture question. Requirements for vCPUs will depend entirely on your workload and for this reason, there isn't much in the way of documentation or calculators to help predict how many vCPUs you'll need for your subscription quota. The best approach is usually to run a stress test to see exactly how much your workload uses. By doing this, you can roughly correlate that X amount of traffic will use Y amount of resources per node and use that as a foundation to make estimates moving forward.

Edit:
In the comment below, @shiva patpi walks through the process of monitoring usage so you can create an educated estimate.

Here is some additional reading on AKS resource reservation and baseline architecture for anyone who is interested:

• Microsoft Learn: AKS resource reservations
• Microsoft Learn: AKS baseline architecture