Swap Partition

Good article. I just wiped my drive and started over like this:
o 350MB partition for swap file
o 1GB partition for OS 9 and 9 apps
o 2.5GB partition for OS X
o Rest of the 20GB drive for /Users and /Applications

I'm still recovering and restoring /usr, /Library, and such that I'd backed up before. We'll see if it was all a disaster in a day or two.

I probably could have gotten away with having everything on one partition as I'd had before but with a separate swap (file) partition.

Oh well.

350MB is not enough for a swap partition. Classic alone takes 1Gig. large apps like OmniWeb easily take 100MB each.
Actually, it should be fine. MacOS X makes swap files that are physically only 80 MB each (when it needs more, it will make another 80 MB swap file). This may not seem like a lot, but it actually is also compressed (which is why real RAM is definitely preferred over VM, any day).

As for Classic, MacOS X only _tells_ Classic that it has 1 Gig to play around with. This is because MacOS 9 needs to know how much memory it has while it's booting up, and so it tells 9 that it has a heck of a lot. I have Classic on right now, and I still only have a single 80 MB swap file (granted, this is in addition to 320 MB of RAM, but if Classic really had a gig, then even without anything else taking any memory, I'd need 680 MB of VM.)

-Bruce Adcock
rharder: have you noticed any performance difference since you added a swap partition?

I second jdog's question!

I find it hard to believe that you're doing this, when a very, very, nice update may only be 2-3 weeks away.

But you know what, somebody has to do it, and if it works, i'm jumping on the bandwagon!


I created a 350MB partition (320MB RAM) and I have seen no real improvements. I imagine that the speed difference would be found if the swap partition sat on another physical drive.

I have my swap file on a separate disk from OS X, but it's not really noticeable. But then, since we both have 320 MB of RAM, I don't think it should be noticeable (since even though it's on a 700 MB partition, I rarely have more than one swap file). I think it's a little faster with a bunch of applications open. It's not the reason why I moved my swap file, anyway. I did it to free up space on my OS X drive.

-Bruce Adcock
First, I had terrible luck splitting the OS X partitions and trying to put Applications and Users on a separate partition. Most of the problems came from that annoying Package Installer that clobbers symbolic links.

But I do have it set up like this:
o 350 MB partition for the swap file
o 1 GB partition for all OS 9.1 stuff
o rest of the 20GB drive for OS X

I haven't notice much difference with the separate swap file, but so many other things changed between my last working setup with one partition and my current setup, that I'm an unreliable witness at best.

Still, if I had to do it again, I think I would take any new computer and immediately make at least two partitions: one for the swap and one for everything else. The separate OS 9.1 partition is only handy for changing boot volumes on startup without using the Startup Disk control panel.

We need a good pager benchmark.

When SoftRAID is ported to OS X I may very well have a good reason to attempt this. I'd like a good benchmark of some fashion to measure the relative benefits of, for example, turning compression on/off.
There are two reasons for adding a swap partition:

1) improving system performance

- this is only going to improve performance if swap is on a separate drive,
even better if the drive is on a separate controller

1) alleviating fragmentation

- this doesnt improve performance, but it puts the swap files on a different
drive so the constant writing to disk wont fragment your file system as
Not to sound like a know it all or someone who wants to rip on anyone who has used the term swap partition. I subscribe to the Darwin users list and was politely corrected that this is not a true swap partition and for the sake of future development to kindly refer to it as a swapfile partition or a dedicated partition for your swapfile.

I have done some testing. I have one iMac and one G4 with two drives in it. The G4 and iMac were very sluggish. They seemed to be dragging quite a bit when I first installed MacOS X. after about 10.0.3 I attempted to move the swapfile to a dedicated space. The performance increases seen on botha single drive and a dual drive setup were noticably different.

On a single drive you will see a very humble performance change. Mainly in the area of disk fragmentation. Because this space is dedicated, I found that it had less area to search and put the data.

On a dual disk drive, I found that the performance was quite noticable. Maybe not in raw performance but starting applications and running classic saw dramatic speed improvements. Now the key to this was bumping my page file up to over 600 MBs in size. This way I was not creating 5 or 6 swapfiles at 70 MBs as the default settings would have it set. This made a signifigant difference for reasons I have yet to determine.

To prove my theory on performance, I did simple timing for opening classic, internet explorer, Adobe photoshop 6.0, and Omniweb.

Classic opened about 5 seconds sooner than before. Internet Explorer gained about a 1 second speed gain. Omniweb gained about 3 seconds, and Photoshop opened closer to it did under MacOS 9.1 native boot.

I have not seen much improvement on screen redraw or finder interaction. Perhaps the only improvement in the finder has been in the column view scrolling between panes. It seems faster but it could be the update to 10.0.4 or just my imagination. Applications still function almost the same but switching between them after my physical memory has been maxed out seems to be a bit faster.

These are all my unscientific conclusions. Has anyone had similar experience?