I want to install ubuntu on 20 gb of free space.The problem is that how to determine how much memory is needed for /,swap and /home.I know swap takes around 1.5 times of RAM but confused about / and /home.Since / is the root and if i allocate 12 gb to it and 4 gb to /home it means that 4 gb for home will be taken from 12 gb alloted for root or the 4 gb would be taken from the 20 gb pool.I am kind of confused , a help would definitely be appreciated.
On most modern machines, its a waste of hard disk space to create a swap space that is 1.5+ times bigger than than the actual installed ram. For example, I have 1 gig of ram and a swap of 1 gig, but the swap space is hardly used. I could easily reduce the swap and my system would work perfectly.
As for / and /home, you allocate them disk space separately since they are two separate partitions. 12 gig is too much for /. Personally I would reserve 5 to 7.5 gigs for / and then the rest for /home because thats where you store most files.