ARM: Add-AzureVMDataDisk requires DiskSizeInGB even for CreateOption attach or fromImage

[colindembovsky]

When trying to create an Azure VM from existing vhds, I create a config and use Add-AzureVMDataDisk to add in the disk configuration.

$vm = New-AzureVMConfig -VMName "demo" -VMSize $size
$vm = Set-AzureVMOSDisk -VM $vm -Name "os-disk.vhd" -VhdUri $osDiskUri -CreateOption attach -Windows -Caching ReadWrite

However, when I try to attach the existing data disk, I have to specify DiskSizeInGB (the parameter is mandatory):

$vm = Add-AzureVMDataDisk -VM $vm -VhdUri $dataDiskUri -Name "data-disk.vhd" -CreateOption attach -Caching ReadOnly -DiskSizeInGB 200

The command succeeds, but when passing this configuration to New-AzureVM, the operation fails stating that the disk Uri exists and that a non-existing uri should be supplied when creating an empty disk. Similarly, if I supply the data disk uri as sourceImageUri and provide a new uri (so that New-AzureVM copies the disk) I get an error stating that "you cannot specify size and sourceImageUri".

I found that if I set the size of the data disk to null in the config, then the New-AzureVM operation succeeds (for both createOption = attach and createOption = fromImage):

$vm.StorageProfile.DataDisks[0].DiskSizeGB = $null

There are 2 solutions:

1. The New-AzureVM cmdlet should ignore the size for CreateOption fromImage or attach
2. The Add-AzureDataDisk cmdlet should not require DiskSizeInGB parameter, setting the value to null if it is not supplied

[singhkays]

I believe this is being fixed in the upcoming release with this PR #620 @huangpf can you confirm?

[markcowl]

@colindembovsky Since this fix just shipped, closing the issue. if you fidn the fix does not solve your issue, please reopen this bug.