Azure Managed Disks became generally available recently and I decided to take the feature for a spin.
With Azure Managed Disks you don’t need a storage account anymore so you won’t be hitting I/O or size limits at the storage account level but the default limit is 2000 Managed Disks per subscription which can be increased if you contact support.
When you create a VM you can now choose to use Managed Disks or Unmanaged Disks, the default is Unmanaged Disks. The Managed Disks show up as resources directly in your resource group, no more drilling down in storage accounts to see what is happening.
When you add additional Managed Disks you can choose to create the VHDs from a snapshot, custom image blob or create one from scratch.
To create a snapshot in the Azure Portal you have to click on New and search for Snapshot. I found this a bit weird, my instinct was to browse to the disk in a resource group or a under a VM and look for a snapshot button there on the disk blade next to Export and Delete but anyway.
You can export a disk to blob storage by using the Export button on the disk blade.
Another great feature of Managed Disks is the ability to change the size and type of a disk but you have to stop the VM first or else you get this error.
Keep in mind you can’t change to a smaller disk size and if you want to use Premium Managed Disks you have to choose a VM family that supports Premium Storage like DS.
The price of Premium Managed Disks is the same as Premium Unmanaged Disks but the price of Standard Managed Disks is different from Standard Unmanaged Disks. For Standard Managed Disks you pay based on the size of the disk provisioned, not the data that is used on the disk. At the time of writing Standard Managed Disks were on a promotional price.
I did a quick comparison on the normal price and provided you use all the space on a disk a full Standard Managed Disk is 20% cheaper than a full Standard Unmanaged Disk. Since is not really practical to have a full disk you’ll have to way up the pros and cons for your scenario. Keep in mind you can start with a smaller disk and resize it later. You can also migrate Unmanaged Disks to Managed Disks but it looks like the only way to do it at the moment is PowerShell.
