How to – Resize an Azure VM

When using VMs in Azure, one of the important things to get right is the sizing. Azure offers several VM series and multiple sizes within each that have fixed allocations of resource such as vCPU and RAM. There are also speciality series that offer additional capabilites like vGPU. Below is a table that covers the majority of series available and their recommended purpose.

There are many reasons you may need to resize a VM, but this post is about how to do it, rather than why. A quick tip, make sure you check out Azure Advisor for some help with this! Regardless of if you run a Windows VM or a Linux VM the below steps are accurate.

The first thing to note, you can resize a VM using any of the ARM tools you like. Such as CLI, Templates etc. However, for this post, I’m going to explain how to do it via the Portal. I would recommend that if you are new to Azure, this is also where you start, until you are familiar with the series and sizes as well as their respective costs.

Azure VMs are deployed on physical servers within an Azure datacenter. These servers are grouped together into hardware clusters. By design, each cluster does not support all VM series that are available. So if you are currently running a DSv3 series you may not be able to resize to a different series, such as an NCv2 immediately. You will however, always be able to resize within your current series.

Basic steps to resize

  • Login to the Azure Portal
  • Select the VM you need to resize
  • Click the Size option under Settings
  • Click the size you would like
  • Click Resize

NOTE: Your VM will need to restart, be wary of Dynamic Public IPs – the Portal should flag this.

Some things to note with the above process, when the VM is active and you click on Size, you will be displayed with a table of series and size currently available in the active cluster, as mentioned earlier. So for my VM, when active I see the below screengrab, note the highlighted number of sizes available.

If I Stop my VM before choosing the Size blade, I am now given the option to choose from the entire range available in the current region. Again note the highlighted number available in the below screengrab.

So, as I am sure you’ve guessed, to resize to any series VM, you must first Stop your VM. This ensure that the VM instance can be moved to a different hardware cluster when it’s started. Changing to a different series obviously takes slightly longer as you have to Stop your VM first etc. However, there is nothing else you have to do for this change.

Hopefully this post has helped understand how to resize and some of the series options you may need to address.

As always, if there are any questions please get in touch!

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