Azure managed disk from source blob (vhd) is not modified (updated)

Question

I am a bit confused with the Azure managed data disk (in ARM) created from VHDs stored in storage source blob. I have a script that creates snapshots on all the storage blobs, but for some reason the changes that are made on the managed disks are not applied to the VHDs.

So the previous dependencies were like:

storage blob -> container -> VHDs -> VMs

Currently:

storage blob -> container -> VHDs -> managed data disks -> VMs

I also have made sure when the VMs were created to use additional data disks, which were created from the existing VHDs. Any ideas about the synchronization?

Answer 1

but for some reason the changes that are made on the managed disks are not applied to the VHDs.

If you create snapshot of managed disk, you can find snapshot via Azure portal, like this:

But if you create snapshot of VHDs(unmanaged disk), the snapshot will not show in Azure portal, you should use Azure PowerShell to list it:

$rg = "Your_resource_group_name"
$saname = "Your_storage_account_name"
$con = "vhds"
$keylist = Get-AzureRmStorageAccountKey -ResourceGroupName $RG -StorageAccountName $saname
$Key = $Keylist[0].Value
$Ctx = New-AzureStorageContext -StorageAccountName $SAname -StorageAccountKey $Key
$List = Get-AzureStorageBlob -Blob *.vhd -Container $Con -Context $Ctx

Output like this:

Answer 2

When you create a managed disk from your own VHD blob your blob is copied to create the managed disk's blob in a different account. The managed disk does not even exist in your account, so taking snapshots of the original blob won't show any updates. You could even delete the original VHD blob and the managed disk will still exist.

If you want to create another VM with a copy of the modified managed disk you need to create a managed snapshot of that disk and use that managed snapshot as a source for your next VM.