Again I cannot suggest others try this, even though I did so on a Cube, PowerBook G4 and DP G4/500 and the systems seem to be running fine and boot in both 10.1 and OS 9.2.1 with no apparent problems. What concerned me most was that on two systems there were "leaf record" errors on the 10.1 volume after the update, even though they seemed to be working fine. Here's the procedure I followed to optimize the disks using another Mac and firewire target disk mode. (This only works if the OS X volume is on a Master IDE position. I have not tried this with any SCSI drives, but Target disk mode will only mount the master IDE drive on the host Mac's desktop.)

After I updated to OS X 10.1 with the update CD (OS X volume in every case was on a master IDE drive. Systems used were:

• PowerBook G4 (running OS 9.2.1 on one partition, OS X 10.1 on the other). It had all the latest updates, etc. installed.
  
  
• G4/450 Cube (using the 100GB Maxtor drive I recently reviewed, with partitions for OS 9.2.1 and OS X 10.1)
  
  
• A friend's G4/733 digital audio system with OEM 60GB IBM drive that had OS 9.2.1 and OS X 10.1 on the same disk.

OS X 10.1 and OS 9.2.1 were running fine on all these systems, however disk fragmentation (as usual) after the update was listed as "moderate" to "severe" by Speedisk.

Since as I noted in my OS X first impressions article yesterday, the new version of Disk Utility cannot verify the startup disk, you can't check for errors on the boot 10.1 disk. I'm always leery of optimizing any disk that has not been checked (preferably with the OS's disk utility from Apple). Therefore I used the PowerBook G4 to do this, booting into OS X 10.1 on it and using target disk mode to mount the system's 10.1 volume that I wanted to check. I wanted to make sure there were no errors of any kind on the 10.1 disk before using SpeedDisk to optimize it.

What surprised me (despite the fact the 10.1 disk util says the disk is verified at each startup), there were errors reported on 2 of the 3 Macs 10.1 updated volumes. These were all "Leaf record" errors -where more records were reported than should have been. Using the PB G4's 10.1 Disk Utility I repaired the disks. I did a verify again after the repairs to make sure the disks were reported as ok.

I then rebooted into OS 9.2.1 on the PB G4 (with the other mac still in target disk mode. As a FYI for those that not used it, you power up the mac with the "T" key held down until you see the large Firewire icon on a blue screen which indicates the mac is in target disk mode). I ran Norton's SpeedDisk which showed the mounted 10.1 disk from the mac in target disk mode in the list of volumes. I selected it, then did a "check disk" to make sure it reported no errors. I then selected optimize disk. After I did this on the first mac, I restarted it and booted into OS X 10.1, ran several apps, connected to the internet, etc. to make sure all was well. I then repeated that procedure for the other Macs.

Note: Although I have optimized 3 Mac's 10.1 disks using the above procedure, I cannot guarantee that others will have the same results. (Matthew Culmore had a disaster using speeddisk on his Pismo's OS X 10.1 partition, even though he said he checked the disk first for errors). Safest is to wait for Symantec to officially reply on 10.1 compatibility or for another company to announce a 10.1 compatible disk optimizer. If in doubt (and not willing to risk your data) - leave well enough alone for now.

After seeing record count disk errors on two G4s after the 10.1 update, even if you don't plan on using Speeddisk, if you can it may be worth using target disk mode with another 10.1 system to check the disk for errors however. I really regret the fact we cannot use Disk utility's Verify feature on the startup disk in OS X 10.1 Although as I noted in my 10.1 first impressions/features article yesterday, the info in 10.1's Disk Utility says a verify is done at startup on the boot disk, I saw errors on two macs that seemed to run fine otherwise after the 10.1 update. These were systems with no 3rd party OS X utilities installed, running the latest firmware updates, using OEM hard drives, with no PCI controller cards, etc. installed.
-Mike

Other OS X 10.1 Articles:
For those that missed yesterday's news, I posted an article comparing OS X 10.1 to 10.0.4 performance tests on my G4/500 DP system (apps, classic PSBench PShop 5.5 tests, Sony FW900 widescreen support, Quake3 game tests with Radeon and Geforce3) and an article with my first impressions of 10.1 regarding the DVD player, CDRW burning (w/my Toshiba retail combo DVD/CDRW drive), interface improvements and more. I've also run tests of Firewire drive mount/sleep issues with 10.1 that notes a problem with some drive types.

For previous OS X (and MacOS) articles, see the Misc Articles page, MacOS section. The topics page links below also include hundreds of reviews, guides, tips and other articles by subject. (Many visitors do not realize the depth or breath of information on this site - so take the time to check out the topics pages!)