Mac hard-disk defrag helped but not much

Last month, I posted that my new MacBook Pro laptop was running more slowly than my year-old iMac – despite the fact that the MacBook Pro had a 2.33GHz Core 2 Duo processor, and the iMac had a 2.0GHz Core Duo processor.

To make a long story short, the one area where the MacBook Pro was deficient was in its hard drive. The iMac uses a 7200RPM drive with a 300MB/sec interface, 8.9ms seek time and 32-step queue. The MacBook had a 4200RPM drive with a 150MB/sec interface, 12ms seek time and 4-step queue. (For more tech details, see the previous blog entry.)

After the blog posting, someone suggested defragmenting the MacBook Pro’s 200GB hard drive. I hadn’t, in part because the machine was new, in part because Apple says that defragging isn’t necessary, and in part because I hadn’t thought of it. Still, what the heck, it’s worth a shot.

I purchased a license for iDefrag, after doing a bit of research into the various products available. The software reported that the disk wasn’t very fragmented, but did indicate that one file in particular – the virtual Windows hard drive that I use with Parallels – was split into about 600 fragments. Ouch.

After running the “Full Defrag” (a many-hour operation that requires booting from a CD), I can say that in general, the defragmenting operation did not help. The defragged MacBook Pro is still noticeably slower to launch and switch applications than the still-fragmented iMac, especially when there’s more than about 10GB of virtual memory in use.

However, there is a startling difference when starting and stopping the Windows virtual machine under Parallels. This process used to take upwards of two minutes, and now takes about 10 seconds.