On Jan 16, 2012, at 3:18 PM, John French wrote: > I'm preparing to move up to Lion by placing Snow Leopard on a separate disk partition, from which I will start up when I need to run those applications that aren't Lion-ready. Are there any authoritative estimates of how large I should make the Snow Leopard partition? Are Apple's technical specifications calling for 5 GB of free disk space sufficient (enough, plus a little bit) without being extravagant? You haven't said how large your drive is. How can we give you an answer without sufficient information? My installation procedure was to divide my internal drive into two partitions of equal size. You might want to consider the same especially if you want to continue to use programs that Lion won't allow to run.