This article is contributed. See the original author and article here.

Understanding your subscription’s VM limits and regional VM capacity is important for 3 main scenarios: 



  1. You are planning to set up a large number of VMs across your labs.

  2. You are planning to use GPUs. 

  3. You need to peer your lab account to a virtual network (VNet)for example, to access a licensing server.


If one of the above scenarios applies to youwe recommend that you open a Support ticket to pre-request capacity.  By pre-requesting capacity, you can:



  • Ensure that your Azure subscription’s capacity limit for Azure Lab Services allows for the number of VMs and the VM size that you plan to use in your labs.  All Azure subscriptions have an initial capacity limit that restricts how many VMs you can create inside your labs before you need to request for a limit increase.  Read the following article to learn more: Capacity limits in Azure Lab Services. 

  • Create your lab account within a region that has sufficient VM capacity based on the number of VMs and the VM size you plan to use in your labs.  This is especially important if you need to peer your lab account to a VNet because both your lab account and VNet must be located in the same region.  It’s important to pick a region that has sufficient capacity before you set this up. 


In this post, we’ll look closer at the process for ensuring that there is sufficient regional capacity for your labs. 


Problem


When your lab account is peered to a VNet, the location of your lab account and VNet determines the region where your labs are created In the lab creation wizard, only VM sizes that have capacity in this region are shown in the list of available sizes.  You may notice that you have the option to show unavailable sizes, but you are prevented from choosing these. 


AvailableSizes.png


You have more flexibility to find available capacity when your lab account is not peered to a VNet.  In this case, Azure Lab Services automatically looks for available VM capacity across all regions in the same geography as the lab account.  However, you still may not be able to choose a VM size if none of the regions have available capacity.  For example, currently in CanadaGPU sizes (e.g. NV series) are not offered in any regions.  As a result, you must create your lab account in a geography that does have GPUs available. 


 


You also can configure a setting called enable location selection (this setting is only available when your lab account is not peered to a VNet).  This setting allows lab creators to choose a different geography from the lab account when they create a lab.  Enabling this option gives lab creators the greatest flexibility to find a region that has available capacity for a VM size. 


 


Regardless if you are using VNet peering or not, you can still run into unexpected capacity issues later.  For example, when creating additional labs or increasing your lab’s VM pool size. 


Solution


We recommend the following process to ensure that you pick a location that has sufficient capacity before you create your lab account and peer to a VNet: 



  1. Refer to the below link which shows VM sizes that are supported by each region. 


  2. Refer to the following link that shows the VM series that correlates with each VM size: 


  3. Open a support ticket to request and reserve VM capacity for your labs.  When you log a support ticket, please include the following information: 

    • Subscription id 

    • LocationRegion 

    • Estimated number of labs 

    • VM size for each lab 

    • Estimated number of VM in each lab 

    • Brief class descriptions for each lab 




If you have any questions on this process, please reach out to us on the forums.


Additional Resources


Refer to the following help topics that provide more details on how regionslocations are configured for a lab:



Thanks,


Your Azure Lab Services Team

Brought to you by Dr. Ware, Microsoft Office 365 Silver Partner, Charleston SC.

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