Azure Virtual Desktop Limitations – Design the Azure Virtual Desktop Architecture

Azure Virtual Desktop Limitations

The Azure platform and Azure Virtual Desktop control plane have some limitations that need to be considered during the design phase to avoid changes in the scaling phase. The Azure Virtual Desktop service can scale more than 10,000 session hosts per workspace, but it is recommended to deploy 5,000 or fewer VMs per Azure subscription per region. This recommendation applies to both personal and pooled host pools based on Windows 10 Enterprise single and multisession. Most customers use Windows 10 Enterprise multisession, which allows multiple users to log on to each VM. You can increase the resources of individual session host VMs to accommodate more user sessions. To manage enterprise environments with more than 5,000 VMs per Azure subscription in the same region, you can create multiple Azure subscriptions in a hub-and-spoke architecture and connect them via virtual network peering, as in the preceding example architecture. You could also deploy VMs in a different region in the same subscription to increase the number of VMs.

Other limitations are related to automation and APIs. Azure Resource Manager (ARM) subscription API throttling limits don’t allow more than 600 Azure VM reboots per hour via the Azure portal. You can reboot all your machines at once via the operating system using PowerShell remoting, which doesn’t consume any Azure Resource Manager subscription API calls. Additionally, for automated session host scaling tools, the limits are around 2,500 VMs per Azure subscription per region, because VM status interaction consumes more resources.

If you are planning to automate session host creation, then you should know that you can currently deploy up to 399 VMs per Azure Virtual Desktop ARM template deployment without availability sets, or 200 VMs per availability set. Also, the Azure VM session host name prefixes support only 11 characters, due to auto-assigning of instance names and the NetBIOS limit of 15 characters per computer account. By default, you can deploy up to 800 instances of most resource types in a resource group, so you have to place resource group structure accordingly. Azure compute doesn’t have this limit.

There are some prerequisites and considerations that need to be checked before admins start deploying AVD. The following are some high-level prerequisites that are explained in subsequent chapters.