Clarification on Ephemeral OS Disk Type for AKS Nodepool Standard_D4lds_v5

Question

I hope this message finds you well. I am currently using Azure Kubernetes Service (AKS) and have a nodepool configured with the Standard_D4lds_v5 VM size. According to the documentation at https://learn.microsoft.com/en-us/azure/virtual-machines/dlsv5-dldsv5-series, the temporary storage for this VM size is SSD.

However, when I check the VM Scale Set (VMSS) in the Azure portal, it indicates that the storage type is Standard HDD LRS. This has led to some confusion on my end regarding the actual type of the Ephemeral OS Disk for my AKS nodepool.

Could you please clarify whether the Ephemeral OS Disk for the Standard_D4lds_v5 VM size is SSD or Standard HDD LRS? Any additional information on how the Ephemeral OS Disk type is determined would also be greatly appreciated.

Thank you in advance for your assistance. I look forward to your response.

Answer 1

Hello Ivan Lee,

Welcome to Microsoft Q&A Platform, thanks for posting your query here.

To clarify, the Ephemeral OS Disk for the Standard_D4lds_v5 VM size is indeed SSD. The VM Scale Set in the Azure portal may be indicating that the storage type is Standard HDD LRS because that is the type of storage used for the persistent disks in the VMSS. The Ephemeral OS Disk, on the other hand, is a temporary disk that is created and destroyed with the VM and is stored on the local SSD of the host machine.

The type of Ephemeral OS Disk is determined by the VM size and is not configurable. In general, VM sizes with "s" or "d" in the name have SSD temporary storage, while those without typically have HDD temporary storage.

Hope this information helps.