Resizing Azure Virtual Machines

I’m regularly asked two questions when it comes to Azure virtual machines which are:

1. Can I resize a VM to give it more CPU and RAM?
2. What is the impact on the VM?

We are used to daily operations using on-premises features such as ‘hot add’  which can increase a VM’s RAM, CPU and HDD capacity without downtime, but can we do the same in Azure?

Can I Resize an Azure VM?

The answer is yes you can within the same series of VM e.g. an ‘A’ to a larger or smaller ‘A’.

When it comes to resizing a VM between different series of VMs the answer is it depends whether the resize is to same hardware or different hardware e.g. a change in chipsets

Undertaking a resize operation is a simple procedure, select your VM and then from the blade select size.

Select your desired size and finally hit select.  You will then see the Notification ‘Resizing virtual machine’

Whats the impact to the VM if I can resize it?

The typical impact to resizing a VM is a restart which can take up to five minutes for the end to end operation to complete.  Therefore I would suggest an outage window is used and a known good working backup before you start!

If you are resizing to a VM onto new hardware (e.g. change in chipset), then the VM will need to be powered off first before the resize operation can begin.

It’s worth noting that if you are resizing VM’s onto new hardware which are in an Availability Set, then all the VMs need to be powered off for the operation to begin.

Final Thoughts

Microsoft have clearly made strides to ensure that resizing a VM within Azure is smoother and easier than ever before.  However ensure that you plan for downtime and perhaps more importantly have a known good working backup before you start work resizing VMs.