Convert VM with managed disks to unmanaged

There are a lot of benefits with managed disks and it is the preferred way to create a new VM. However because of my tight budget, I wanted to move to unmanaged. I did not expect the costs to continue when the VM was stopped. It was because of the managed storage disks(s).

I found this SO answer of Jason Ye - MSFT.

$sas = Grant-AzureRmDiskAccess -ResourceGroupName "[ResourceGroupName]" -DiskName "[ManagedDiskName]" -DurationInSecond 3600 -Access Read  
$destContext = New-AzureStorageContext –StorageAccountName "[StorageAccountName]" -StorageAccountKey "[StorageAccountAccessKey]"
$blobcopy=Start-AzureStorageBlobCopy -AbsoluteUri $sas.AccessSAS -DestContainer "[ContainerName]" -DestContext $destContext -DestBlob "[NameOfVhdFileToBeCreated].vhd"

I had to create containers in the storage account but I had copied both the OS and the Data disk to the blob storage as .vhd file.

I used this powershell script and the template to create the vhd from blob storage. The datadisk can be added later in the web gui.

1. Login-AzureRMAccount
2. Get-AzureRmSubscription
3. Set-AzureRmContext -SubscriptionName "my subscription name here"
4. $sas = Grant-AzureRmDiskAccess -ResourceGroupName "resourcegroup" -DiskName "manageddiskname" -DurationInSecond 45000 -Access Read 
   $destContext = New-AzureStorageContext –StorageAccountName "storageaccount" -StorageAccountKey "myprivatekey"
   $blobcopy=Start-AzureStorageBlobCopy -AbsoluteUri $sas.AccessSAS -DestContainer "vhd-containers" -DestContext $destContext -DestBlob "givetheunmanageddiskaname.vhd"
5. Get-AzureStorageBlobCopyState -Container "vhd-containers" -Blob "givetheunmanageddiskaname.vhd" -Context $destContext –WaitForComplete

My mistake was to use the 3600 value for ‘DurationInSecond’ which is just an hour (60 sec, 60 minutes). The 512 gb datadisk could not be copied to blob storage within an hour (or two). Found out that an hour was also insufficient when I found ‘Get-AzureStorageBlobCopyState’.

Because I already had a vnet from my vm with managed disks, I used this template to create a new vm with the os disk from blob storage: https://github.com/Azure/azure-quickstart-templates/tree/master/201-vm-specialized-vhd-existing-vnet

If you do not have a vnet yet, you should use https://github.com/Azure/azure-quickstart-templates/tree/master/101-vm-from-user-image The deploy to azure button is a useful tool!

Once you have a new vm with an unmanaged disk up and running, close it to add the data disk. Once you have done that and have a remote desktop connection, go to disk management and bring the datadisk online again. It took me some time to get my head around the ASM and ARM differences in the powershell tooling. Also because there is now Azure Cli and a cross plat powershell 6.0

The cloud is moving fast, so hop on. Don’t miss out!

Good luck!