Disk could not be unmounted

[JoBoy]

I boot from a clone on a separate hard drive and open Disk Utility on the clone. I then select Macintosh HD and attempt to repair disk. I get a message: The disk "Macintosh HD" could not be unmounted. It also happens when I try to run iDefrag from the clone to defrag Macintosh HD. Repair Permissions works fine. So does Verify Disk. I'm now running OS X v 10.5.6. This has not happened in the past with other versions of Leopard, although I'm not absolutely sure whether this problem started with 10.5.5 or 10.5.6. It does NOT happen when I repair disk on Sandbox while booted from the same clone. Sandbox and Macintosh HD are partitions on the same disk. Any suggestions?

[dnanian]

That seems weird, since your Sandbox would be explicitly referencing your Macintosh HD.

In general, I'd suggest renaming the copy to the same name as the source, then starting up from it and trying iDefrag.

[JoBoy]

I just edited the first entry to provide more information. Does the edited version of the question shed any additional light?

[JoBoy]

Dave: I posted this version on the Apple Forum just in case there's a known Apple bug. It includes more info than my posts here. Does it clarify the issue?

First, I make a clone of my main internal hard drive using SuperDuper. The clone is located on a second internal hard drive. I then boot from the clone and open Disk Utility on the clone. I then select Macintosh HD located on my main hard drive and attempt to Repair Disk. I get a message: The disk "Macintosh HD" could not be unmounted. It also happens when I try to run iDefrag from the clone to defrag Macintosh HD. Repair Permissions works fine. So does Verify Disk which reports that the volume is just fine. The problem does NOT occur when I Repair Disk on other volumes while booted from the same clone. I have no other known difficulties with the Macintosh HD volume.

I'm now running OS X v 10.5.6. This problem has not happened in the past with earlier versions of Leopard, although I'm not absolutely sure whether this problem started with 10.5.5 or 10.5.6. Any suggestions?

[dnanian]

I think I tried to explain what you should do, JoBoy. Did you try what I suggested?

[JoBoy]

Do you mean that I should have two volumes using the same name? That's counterintuitive and I'm hesitant to try it. I've never shied away from any of your advice, but this one makes me jumpy.

[JoBoy]

OK. I tried it. Repair Disk on Disk Utility worked fine, but one of the Macintosh HD icons disappeared from the desktop. I haven't tried iDefrag yet due to the time commitment. I'll try it later. It is very confusing when looking at the desktop and also the choices on the startup disk item on system preferences, but Disk Utility and iDefrag are very useful because they show the hard drive identity as well as the volume name. Thank you. I apologize for the hesitation. This whole problem must be in the system since it involves Disk Utility and another application. Is it a bug or a feature?

[dnanian]

It's because something you're running is referencing files including the volume name. So, it's locating them on the original drive, rather than the copy, and that makes the drive busy.

Naming the backup the same means it finds the file on the startup drive (first), rather than hunting for its original named volume.

[JoBoy]

OK. Your last answer got me thinking. I'm not deliberately running anything except 5 login items. I tried deleting them one at a time to see if it would end the problem. It did. Palm Desktop Background is the culprit. I have a Palm Centro pda. I'm doing an Automator app to remove it from the clone before I do maintenance on Macintosh HD. There's no need to restore it after the maintenance because I don't use the clone except for maintenance and backup. I run daily scheduled backups and I've tried a test backup. It restores the Palm Desktop Background app during the update. Problem solved. Thank you. Sorry for the chicken attitude I had when you suggested a solution.

[dnanian]

No problem. I wouldn't suggest things that are dangerous without warning you!