What are 'managed' and 'non-managed' availability sets?

Question

I'm trying to provision an Azure VM programmatically and I got this:

An unhandled exception of type 'Microsoft.Rest.Azure.CloudException' occurred in mscorlib.dll Additional information: Addition of a VM with managed disks to non-managed Availability Set or addition of a VM with blob based disks to managed Availability Set is not supported. Please create an Availability Set with 'managed' property set in order to add a VM with managed disks to it.

Unfortunately I don't understand the distinction its talking about with managed and non-managed availability sets. The API I am using for creating availability sets doesn't even obviously have such a flag/property. What conceptual background info am I missing here?

Gramercy

Answer 1

I'm afraid it says what it should. And that state is clear.

You can't mix managed and unmanaged resources and availability sets. So if you want to have managed disk, VM it has to be created in managed availability set. Please follow this link to see more descriptive explanation at their help center.

Gertudegerty

Answer 2

When you create an availability set through the Azure Portal or through the ARM PowerShell module you can choose whether it will contain managed or unmanaged disks.

The following image shows the difference between both types (taken from this video):

Basically a managed availability set can only contain VMs with managed disks. A managed disk will automatically place the VM images in a different storage unit, so that if one of them fails it won't take down all of them.

There is more information here: https://learn.microsoft.com/en-gb/azure/virtual-machines/windows/managed-disks-overview

Calculous

Absolutely well written! However, I wonder is there a point keeping this checkbox since Azure already plans to deprecate the unmanaged disk by September, 2025. – Barbellate