Before we begin to install a virtual SBS Essentials, one has to determine what you want to do as far as planning for disk space.
While you can follow the SBS blog for the how to use a config file to set the drive sizes, you can also use Robert Pearman’s GUI scripting tool http://gallery.technet.microsoft.com/SBS-2011-Essentials-Answer-5bfc015a to set the configuration.
That’s the hard drive space used after about 22 computers, several with archived backups, along with two stored backups for computers that are now removed from the office…. When I did the very first backup of each computer, it was about 1T for the whole shebang. The total of the drives that are being backed up is about 2T worth of stuff (on my box a bunch of ISOs that probably don’t need to back up. So it’s about a 50% reduction of the drive space of the computers being backed up.
You can’t choose less than 60 gigs for the OS drive. Then determine what your data drive is. But be careful about the 2T brick wall. Not that long ago Terrabytes were considered insanely huge. Now we think a Terrabyte is normal. There’s an issue when you have a drive greater than 2T on a Windows backup… Windows Backup has a 2T limit. A good discussion is here: http://homeservershow.com/forums/index.php?/topic/2212-backup-limitations-a-counterpoint/ Chunk down your data so that you can get it backed up.