Everyone knows two things about saving money on Azure VMs: 1, chose a smaller size and 2, turn it off when you are not using it. It turns out that the second one has an additional demand: you need to not use premium disks.

What are premium disks?

These are great! Great for performance and together with managed disks you get 99.95% SLA from Microsoft even though you are not using scale-sets or redundant machines. The disks are managed in such away that they are copied between different parts of the hardware, so that the whole datacenter needs to be taken down to take out your disks.

Read more about premium storage here: https://docs.microsoft.com/en-us/azure/virtual-machines/windows/premium-storage

The problem?

But if premium disks are so great, why not use them? Of course, you should but if you are like me and have environments which are primarily not production environments, but rather smaller dev-focused machines, you do not need them. The thing is that if you use SSDs you need to pay for the full disk, all the time even the parts you are not using. So even though you might use 50 GB on a disk you need to pay for the full 127 GB, and you still need to pay for storage even though your machine is turned off. Still the cost might not be that big, but you might have several machines, or several disks and the cost stack up.

Here is a screendump from a subscription for two machines that has not been active the current period, cost is in SEK.

So only use premium disks when they are needed. They are a great feature of IaaS and should always be used in production machines, but in a dev-scenario choose standard HDD.

How do I change it?

It is simple: Turn off/stop you machine and find the “disks” setting. It is usually under networking on the VM in the Azure portal.

Click the Disks and in the list to the right, you can see what type of disks you are using. Click the disk you need to change.

Change Account Type to Standard HDD and click Save.