Azure capacity of s and non-s instances

Question

There are many pairs of VM type that vary only in presence of lack of s, such as D4d_v5 and D4ds_v5. s indicates support for premium storage. The instances always seem to be same price with or without s.

Let's assume I don't care about premium storage. What should I choose? Are these separate pools of instances or are they same or can non-s instances be allocated on s hardware but not the other way around?

It seems obvious that I should choose non-s if I don't need premium storage, but I'm concerned about capacity and stock outs, so knowing the above would help (e.g., if I find D4d_v5 out of stock, should I bother trying D4ds_v5 in an automated fashion).

Answer 1

Hello Travis, Welcome to MS Q&A

In Azure, VM types with and without 's' (indicating support for premium storage) are generally considered separate SKU pools. This means that if a non-s instance (e.g., D4d_v5) is out of stock, it is possible that the corresponding s instance (e.g., D4ds_v5) might still be available.

However, non-s instances cannot be allocated on hardware reserved for s instances, and vice versa. Therefore, if you encounter a stock-out situation with a non-s instance, it is indeed worth trying the corresponding s instance in an automated fashion to check for availability.

References:

https://learn.microsoft.com/en-us/azure/virtual-machines/sizes/overview?wt.mc_id=knwlserapi_inproduct_azportal&tabs=breakdownseries%2Cgeneralsizelist%2Ccomputesizelist%2Cmemorysizelist%2Cstoragesizelist%2Cgpusizelist%2Cfpgasizelist%2Chpcsizelist#vm-size-and-series-naming

Please let me know if any further questions

Kindly accept answer if it helps

Thanks

Deepanshu