Macos – How to make the Users Directory a different partition in Snow Leopard

NOTE: See (also) a corrected/improved answer in the question itself.

Following solution worked for me:

Open a terminal and backup com.apple.dynamic_pager.plist which you're going to change in a second:

$ cd /System/Library/LaunchDaemons
$ sudo cp com.apple.dynamic_pager.plist{,_bak}

convert binary plist to xml:

$ sudo plutil -convert xml1 com.apple.dynamic_pager.plist

and open it with your favorite text editor

$ sudo vim com.apple.dynamic_pager.plist

it'll look something like this:

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
 3 <plist version="1.0">
 4 <dict>
 5     <key>EnableTransactions</key>
 6     <true/>
 7     <key>HopefullyExitsLast</key>
 8     <true/>
 9     <key>Label</key>
10     <string>com.apple.dynamic_pager</string>
11     <key>OnDemand</key>
12     <false/>
13     <key>ProgramArguments</key>
14     <array>
15         <string>/sbin/dynamic_pager</string>
16         <string>-F</string>
17         <string>/private/var/vm/swapfile</string>
18     </array>
19 </dict>
20 </plist>

In line 17 modify /private/var/vm/swapfile (e.g. /Volumes/partition2/swapfile), save and close your editor (":x" will do both in vim).

convert the plist file back to binary:

$ sudo plutil -convert binary1 com.apple.dynamic_pager.plist

After rebooting your Mac you should find the swapfiles in the directory you specified.

If you run into any problems you can restore the backup you created in the first step with:

$ cd /System/Library/LaunchDaemons
$ sudo cp com.apple.dynamic_pager.plist{_bak,}

Ok I started doing this as I dint get any responses for sometime.

1. Rebooted and booted from the Snow leopard install disc. To answer my own question, there is no problem in using disk utility with GUID partition map which is what you have if you started out with leopard. You can see that information at the bottom of DU before doing anything.

2. Opened Disk utility. Split into two partitions. [A] and [B]. [A] holding existing partition and [B] a fresh partition naming it as SL HD for identification. [A] appears on top of [B].

3. Went back to install screen and proceeded install Snow Leopard(SL) into [B]. After install [B] is set as the active partition (a.k.a Startup Disk in Mac parlance), rebooted and got into migration assistant.
4. Selected [A] as migration source and selected few folders(docs, pics) and network settings. Dint move Apps etc.
5. After moving rebooted into SL and everything looked fine. Noticed that some apps that I dint choose to move were still running in SL (mmm). Since I dint want them, went into the [A] part from finder and trashed applications folder, system and library.
6. Now since SL was working fine wanted to reclaim the space occupied by [A] and give it to [B].
7. Rebooted into install DVD. Opened disk utility. Found that partition wouldn't allow to resize [B] upwards. :(. Seems you cannot resize partitions with OS installed upwards(probably because it has the bootloader portion for that partition).
8. So after investigating some commercial partioners like iPartition, decided to investigate inexpensive approaches.
9. Found Restore option in DL which allows you to pick a source partition and let it be cloned over to a another partition.
10. Search for "Restore in disk utility" in google before doing it as you need to verify and repair disk permissions.
11. After that select Restore, select [B] as source and [A] as destination. Hit restore.
12. Now [A] has a cloned copy of SL. In utilities select startup disk and select [A].
13. Reboot and check if SL is working from [A].
14. Reboot back into install DVD. delete [B] and resize [A] to fill the full size. This will work as your resizing downwards and there is empty space left by [B]. Apply and your done.