Changing swap file location on tray-loader iMacs

Question

This is not a question, but something I discovered that makes my old tray-loader iMac (the oldest iMac models) run Mac OS X much better.
As you may know, these oldest iMacs have an 8GB size limit on the boot volume. The largest stock drive on these iMacs was 6GB. That means if your upgraded hard drive is larger than 8GB, it must be partition so that the first partition is under 8GB (7.78GB on my iMac), and it must be the boot partition where the OS is installed (whether it's Mac OS X or 9).
In my case, I have a roomy 120GB hard drive (I believe the useable limit on these iMacs is 128GB). The first partition is just under 8GB, the second partition is the rest of the space, about 104GB. I have used every trick out there to move files (such as the iTunes music folder and most of my user/documents files) off to the second partition, to make free space on the boot partition as large as possible. So I have 3.5GB free on my 8GB boot partition. This is about 40% of the volume's total space so it seems pretty good, until you realize that most recent Macs have much more than the TOTAL 8GB I have, as free space on the boot volume. Mac OS X was just not designed to work well with small boot volumes...
Mac OS X uses the free space on the boot volume for its virtual memory "swap file." Considering these old iMacs max out at 512MB of RAM, virtual memory is being used quite a bit. But since space on the boot volume is very limited, low RAM and lack of free space can lead to performance issues. Here's what I observed. When I initially started up my iMac, I had about 3.5GB of free space. Over time, as I used more and more apps, that free space would diminish until I had only about 600MB remaining (as reported by a Finder window). At the same time, I noticed performance getting bogged down and more "chugging" sounds coming from the hard-working hard drive.
I've known about changing location of the swap file, but never tried it until recently. During the Mac OS X boot process, the Mac sets the location of the swap file. By default, the swap file resides on the boot volume (I believe most other Unix-based systems use a dedicated "swap partition" for the swap file). Since most recent Macs have large drives set up as one partition (and there is plenty of free space), and since many users have upgraded their RAM (and virtual memory is not as critical), swap file location is usually not an issue, and there is certainly no need to change the swap file location. However, on my iMac with an 8GB limit on the boot volume and 512MB of RAM, it made a noticeable difference.
I found one set of procedures on the web that was much better than the others I found for changing the location of the swap file.
http://www.math.columbia.edu/~bayer/OSX/swapfile/
On this page, there are two choices for Panther users. I used the one that works for both Panther and Tiger, because it appeared to me to be more straightforward. The author intentionally keeps the instructions somewhat technical to discourage users who are not technically inclined. I don't consider myself to be too "geeky," but I can follow instructions and type a few commands in Terminal.
After I changed the swap file location to a large mostly empty volume, I noticed much better performance when I have many large apps open at the same time. Performance no longer degrades over time, and the free space on my boot volume remains a constant 3.6GB.
The reason for this post is to share this information. Some users of these old iMacs may be noticing the same issues I had. This is a possible solution. However, if everything is OK with your set up, there is no reason to change the swap file location. If you try it, be sure to take the usual data backup precautions.
If anyone else has experience with changing swap file location, please post your comments here.

Answer 1

Problem has been solved:
background.setCapability(Background.ALLOW_IMAGE_WRITE);Thanks everybody for reading this :)