"Available memory 9 GB Available; 8 GB Required" when creating Azure AKS on Azure Stack HCI

Question

I try to create Azure AKS cluster on Azure Stack HCI but it shows the error with "Available memory 9 GB Available; 8 GB Required".
The avaiable memory is already more than the required memory.
How can I pass the system check process of this step?
Thank you.

Answer 1

The AKS-HCI Management Cluster VM that will be deployed needs 8GB, but as with all virtualization platforms, there's a little extra memory overhead required per VM, which in this case, will mean that the AKS-HCI cluster VM needs ~8.1GB. I don't know the logic behind WAC's memory assessment, and it may be that you need 8GB + some additional headroom to be able to deploy, but this is not described in the error message.

One point to note, even if it did let you deploy the 8GB RAM VM, once deployed, you would have no remaining memory to deploy an AKS-HCI target cluster to test/run any apps/workloads - you'd need at least another ~12-15GB RAM to deploy the Load Balancer, Control Plane and worker node for your target cluster.

Hope that helps,
Matt

Answer 2

@KarishmaTiwari-MSFT - this is for a target cluster, which can only be deployed once the initial management cluster has been deployed. The management cluster requires 8GB, your target clusters will require additional memory, directly related to the # and size of Load Balancer, of control planes, and worker nodes.

This is one of the reasons why, for a production deployment, we recommend (https://learn.microsoft.com/en-us/azure-stack/aks-hci/system-requirements#compute-requirements) a physical system with at least 256GB RAM and 16 physical cores, but for evaluation purposes, having 64GB RAM should give you enough headroom to run the Host OS, the management cluster (8GB) and a few small target clusters.

Answer 3

As shared in the answer above, this error implies that it may need more than 9 GB potentially and thus cannot move forward with the deployment.

I couldn't find an exact mention of this error in any official documentation but there is a mention of this issue in the form of a FAQ related to PowerShell deployment.

Learn more about known issues for Azure Kubernetes Service on Azure Stack HCI.