Using Azure Virtual Desktop with Spot Instances

Question

Hello,

I am a business owner looking to configure Azure Virtual Desktop (AVD) to access CRM while outside the office. I want to use session hosts on Spot instances since they are cost-effective. However, when configuring it via the AVD portal, the computer doesn't give me any checkbox for Spot instances.

I also tried moving a prebuilt Spot VM, but the system did not allow me to move it, even through PowerShell. Can anyone provide guidance on how I can configure AVD to use Spot instances?

Thank you!

Answer 1

@CBC Spot instances are a bit risky for AVD as you can't make any predictions on their availability. The user might get disconnected and lose any unsaved work.

Using automatic scaling you can achieve similar cost savings with a better user experience since you can warn the user about his session being disconnected when a scale-down event is happening. I checked with the product team, and they also recommended using our autoscale service to manage costs for AVD. You could also look at various VM types to meet your cost and performance needs.

In my opinion, VDI is not a valid workload for Azure Spot VMs.  Azure SPOT VM docs say Deploy workloads that can handle interruptions and don't need to be completed within a specific period of time. Run workloads for development, testing, quality assurance, advanced analytics, big data, machine learning and AI, batch jobs, rendering and transcoding of videos, graphics, and images at a very low cost.

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Answer 2

Hi,

If you want to use Spot VM you can first create it separately and join it to domain/Entra ID. Next you can Generate registration key and register the VM to the host pool. Please see links below for details:

Generate a registration key

https://learn.microsoft.com/en-us/azure/virtual-desktop/add-session-hosts-host-pool?tabs=portal%2Cgui#generate-a-registration-key

Register session hosts to a host pool

https://learn.microsoft.com/en-us/azure/virtual-desktop/add-session-hosts-host-pool?tabs=portal%2Cgui#register-session-hosts-to-a-host-pool

You should read above document in its entirety for other key points.

NOTE: Spot VMs can be evicted at any time, which may result in the user(s) losing data. Recommend you choose VM size with low eviction percentage (0-5%) and keep in mind this percentage will vary over time/days.

If something is unclear or you need assistance with a specific step, add a comment below.

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Thanks.

-TP