Don't import appliances if there's not enough space on disk

[tgarcia]

When importing appliances, it is common that the appliance file is smaller than the actual guest disk size. Given that, if you are importing an appliance and you don't know the guest disk size, you'll get an error after the host disk is full. Some import operations may take up to a hour, or more, so if you get the error after the import cannot continue, this is a little frustating to see the time you could save.

E.g.: I have a 20GB appliance the allocates more than 100GB. I was trying to import it on a disk with 80GB free. After 40min importing, I got the allocation error.

So, my suggestion is to show the final size for allocated space in the import dialog, or maybe even check the drive that the user is placing the VM disk and give a message like 'You don't have enough space to import that machine here', or something like that.

[Frank Mehnert]

Valid point.