VM Reserved Instance Purchase Error due to Quota

Question

Currently, there is a Compute quota of 500 cores of DSv3, with 400 cores in use at normal pay-as-you-go pricing 24x7. The intention is to purchase Reserved Instances (RIs) to save on costs on those 400 cores in use.

However, an error occurs when attempting to purchase RIs, indicating a lack of quota. What could be the reason for this error? Is it necessary to request additional quota for purchasing RIs since the cores are currently in use?

Answer 1

Hi Bonny

Thanks for using the Q&A platform.

When you purchase Azure Reserved Instances (RIs), you’re not buying compute capacity, you're pre-paying to get discounted pricing on VMs you already use (or will use in the future).

However, the process of reserving instances still performs a quota check, not to block you but to ensure that capacity can be guaranteed if needed.

Suppose your current quota usage is already close to the limit (e.g., 400 used of 500 DSv3 cores). In that case, Azure may block the reservation purchase because it technically calculates if it could fulfill that reservation capacity fresh, as if you needed 400 cores available on demand.

This check can fail even if you're not actually launching new VMs.

You do not need extra quota to apply reserved Instance pricing to existing running VMs, but you might need extra quota to complete the RI purchase because the system simulates provisioning those VMs.

Kindly submit a quota increase request to Microsoft support for the specific VM size family (DSv3) in the specific region.

Additionally, find: https://learn.microsoft.com/en-us/azure/azure-resource-manager/management/azure-subscription-service-limits
https://learn.microsoft.com/en-us/azure/cost-management-billing/reservations/save-compute-costs-reservations
You can mark it 'Accept Answer' and 'Upvote' if this helped you

Regards,

Obinna

Answer 2

Hello Boony , Welcome to MS Q&A

The error you're encountering when attempting to purchase Reserved Instances (RIs) is likely due to a quota restriction on your subscription. Even though you have 400 cores in use, Azure requires that you have enough quota available to cover the Reserved Instances you wish to purchase. This is to ensure that you can fully utilize the reservation benefits.

Here are some steps you can take to resolve this issue:

Request a Quota Increase: You may need to request an increase in your vCPU quota for the specific VM series you are using. This can be done through the Azure portal by selecting the "Request quota increase" link in the error message.

Check Subscription Scope: If your reservation is scoped to a single subscription, ensure that the subscription has enough vCPU quota available. You can also consider changing the reservation scope to "Shared" to apply the reservation benefits across multiple subscriptions.

Contact Support: If you continue to face issues, you can contact Azure support to request an exception for your subscription.

For more detailed guidance, you can refer to the Azure documentation on troubleshooting reservation issues.

Pls let me know if any further ques

Kindly accept answer if it helps

Thanks

Deepanshu

Answer 3

Hi,

Please confirm you are attempting to purchase Reserved Instances in the Azure portal, via below link:

https://portal.azure.com/#view/Microsoft_Azure_Reservations/ReservationsBrowseBlade/productType/Reservations

Reason I ask is, the way you describe sounds like you may be purchasing a Capacity Reservation, which is different. When you try to purchase capacity reservation it will warn/block you if the purchase will exceed quota.

Please click Accept Answer and upvote if the above was helpful.

Thanks.

-TP