min_disk/min_ram set too high for vhds

In the code, (nova/compute/api.py)

        #disk format of vhd is non-shrinkable
        if orig_image.get('disk_format') == 'vhd':
            min_ram = instance['instance_type']['memory_mb']
            min_disk = instance['instance_type']['root_gb']
        else:
            #set new image values to the original image values
            min_ram = orig_image.get('min_ram')
            min_disk = orig_image.get('min_disk')

There are two problems with this. First, min_ram has nothing to do with the vhd format, and should definitely be coming from the original image.

Secondly, its not clear to me that vhd's aren't shrinkable, or that you're even required to shrink them? Even if you are required to shrink it to fit and can't in a particular case, min_disk is just advisory. There will still be a check during the boot step to ensure you're not doing anything wrong.

My feeling is that, it is better to fail slow in the case where the image is too large than to fail fast incorrectly in the more likely cases where the image is small enough to fit.