Are the new AMD Dads v6 VMs suitable for production use in Azure Kubernetes Service, given their lack of support for Ephemeral OS disks?

Question

Hi,

I was excited about the General Availability release of AMD v6 VMs- Dadsv6. However I noticed that they do not support Ephemeral OS disk, although they have big enough local disc. Azure Advisor says we should use Ephemeral OS disk on AKS.

Therefore my conclusion is that the new Dadsv6 VMs are suboptimal for production use in Azure Kubernetes Service.

Am I correct in my conclusion?
What is the reason why Dadsv6 doesn't support Ephemeral OS disk and Dadsv5 does support it?

Answer 1

@JP

Thanks for your question. For optimized performance we do recommend using ephemeral OS disk for AKS. Details about this can be found here. Ephemeral OS disks are stored only on the host machine, just like a temporary disk. With this configuration, you get lower read/write latency, together with faster node scaling and cluster upgrades.

When selecting the VM size for your node pool you can filter if Ephemeral OS disk is supported.

Unfortunately, I am not able to share the specifics of why the Dadsv6 does not support ephemeral OS disk. I believe this could be related to v6 utilizing NVME disks. I would recommend sticking to Dadsv5 or Ddsv5, AKS will update the recommended VM types when new ones become available.

Hope this helps! Let me know if you still have questions and I will do my best to assist.

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Answer 2

We faced the same thing, we wanted to move all our v5's to v6 as there are so many restrictions capacity wise for v5 in our region while v6 is plenty. It is a bit weird that something like this is overlooked because when you look at the properties of the VM series itself, it has EphemeralOSDiskSupported=True though it does use nVME disk placement but still in theory it should support it however if you try you will see the error message that there is no space for Ephemeral disk... EDIT Actually our issue is with the series Epdsv6 and not Dadsv6. Epdsv6 should support ephemeral disk but doesn't. Dadsv6 doesn't have support.