Dlatu1983
This is how I did it for my setup. I have a maxtor 120 gig hard drive, that I setup with 3 partitions. (Make sure you back-up any valuable data first!!!!)
The first partition I made 10 gigs for all the system software, with everything I have installed for the system, it uses up 4.41 gig (this includes Xcode tools and fink installations). Now this partition is dedicated for only the 10.3 system files.
The next partition that I made was another 10 gig for my applications, which right now is using up about 3.91 gig, again this partition is my 'Applications' folder. (I'll get to how to do this in a minute) And my third partition is the rest of the hard drive for the Users folder.
Now you may want to think about how much you want to dedicate to each partition, and I'm still playing around with this setup, and may change it. But as it stands, I feel that I've left enough room on each partition for any 'extra' junk that I may acquire. (I can change this if I want, because I have plenty of space for backup on extra hard drives.)
Now, here is how I setup my system: After doing a clean install of 10.3 on the 'system' partition, I use the new finder command (right click or control click) create archive on the application folder. When this is done I drag the archive to the new 'application' partition, and expand the archive. I then drag all user data to the new 'user' partition.
Now the next part can may be able to be done differently, but the easiest way that I know how is by using the terminal and vim.
Following the instructions from:
http://www.kung-foo.tv/xtips.php#1
I use vim to do the following (which you will have to have root user enabled via netinfo manager.)
at the prompt type the following:
sudo vim /etc/fstab
if will ask for your password, then open the file. When the file opens I add the following 2 lines.
LABEL=Users /Users hfs rw 1 2
LABEL=Applications /Applications hfs rw 1 2
then save the file.
Then restart your computer, and hold down the apple-s key to boot into single user mode.
From there, type:
mount -uw /
to mount the system partition. Then
cd Applications
rm -R *.app /Applescript /Utilities
This will remove the Applications data that OS X installed on your 'system' partition ( you don't have to do this, but you will gain a little bit of disk space back by doing so.)
then type:
cd ../Users
rm -R /your_user_name /Shared
Again same as before, not necessary, but will save you drive space.
then type:
exit
and your computer will start up as normal.
The two lines you typed in the fstab file act as an alias to your applications and users folders, which are technically on separate partitions, but as far as OS X is concerned, are on the OS X partition. The benefits of this, are as you stated, you can do a complete re-install of OS X without affecting your applications or users data.
If you do have to do a re-install, you'll have to edit the fstab file again, and do the single user removals again to re-setup your system. Ya it can be kind of a pain in the *ss, but much easier than re-installing every application you own, and worrying about all your user preferences and such.
If you need any further explanation or have any other questions, feel free to contact me.
Good luck.