I think your major problem in determining the smallest partition size may be disk caches which to some extent will depend on how much memory you allocate to the Snow Leopard under Parallels. I wouldn't be stingy. HD drive space is extremely cheap these days, even considering flooding problems. Jens On Jan 17, 2012, at 9:32 PM, John French wrote: >>> ... Are there any authoritative estimates of how large I should make [a] Snow Leopard partition? .... > > Ron Steinke replied: > >> You haven't said how large your drive is. How can we give you an answer without sufficient information? > > The information is quite sufficient. What difference would it make if my drive were 250 GB or 2 TB? Nothing in the size of the drive has anything to do with determining the smallest disk partition that can comfortably accommodate Mac OS X 10.6.x. > >> 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. > > Trust me, I won't bother the list if the problem I'm facing is nothing more than how to divide by two. :-) Again, I'm looking for the smallest partition from which Snow Leopard can run without problems; nothing more. This is not a partition whose contents will grow over time, so even allowing for significant expansion is unnecessary. > > Onward, > john > _______________________________________________ > X4U mailing list > X4U at listserver.themacintoshguy.com > http://listserver.themacintoshguy.com/mailman/listinfo/x4u Jens Selvig ...Lost in Montana...