Disk Utility Error: Couldn’t unmount disk

Question

Disk Utility Error: Couldn’t unmount disk

I have my MacBook Pro hard drive partitioned into 3 segments.

I have an external FW drive i use as a startup disk to do maintenance on my MacBook internal drive.

Tonight i was running off the external drive and opened Disk Utility to do volume verifications on the 3 MacBook internal partitions. Two of the verifications went off without a hitch. The third partition kept coming up with this error: No other programs are running.

This is the error log entry:

**********

2013-03-05 19:28:55 -0500: Disk Utility started.

2013-03-05 19:29:07 -0500: Verifying volume “Personal”

2013-03-05 19:29:07 -0500: Starting verification tool:

2013-03-05 19:29:08 -0500: Error: Couldn’t unmount disk.2013-03-05 19:29:08 -0500:

2013-03-05 19:29:08 -0500: Disk Utility stopped verifying “Personal”: Couldn’t unmount disk.

2013-03-05 19:29:08 -0500:

**********

I tried disengaging spotlight. Same error.

I tried restarting finder. Same error.

I tried clicking "dismount" in Disk Utility. Same error.

I tried rebooting in safe mode. Same error.

But if i reboot and run off of the MacBook Pro OS, i can check this partition without a problem.

Heeeeeelp!

🙂

Paul

MacBook Pro, OS X Mountain Lion (10.8.2), 2.2 Ghz Intel Core i7

Posted on Mar 5, 2013 7:46 PM

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Answer 1

baltwo

Level 9

62,362 points

Mar 6, 2013 10:54 AM in response to Paul Williams3

Normally indicates that some file's running on that volume. Run lsof /Volumes/"volume name" in the Terminal app to see which file might be open.

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Answer 2

Mar 7, 2013 4:14 PM in response to baltwo

I'll try that right now and post the output. Give me 30 minutes. Thank you!

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Answer 3

Mar 7, 2013 4:23 PM in response to baltwo

This is what it kicked out:

Last login: Thu Mar 7 19:17:16 on console

Pauls-MacBook-Pro:~ MyMac$ lsof /Volumes/Personal

COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME

UserEvent 160 MyMac 61r DIR 1,3 40256 137 /Volumes/Personal/Scanned

UserEvent 160 MyMac 62r DIR 1,3 1496 2 /Volumes/Personal

Pauls-MacBook-Pro:~ MyMac$

Any ideas?

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Answer 4

baltwo

Level 9

62,362 points

Mar 7, 2013 7:41 PM in response to Paul Williams3

Yes, UserEvent, with PID 160, is running. Use this in the Terminal to kill it:

kill 160

That should allow unmounting the volume.

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Answer 5

Mar 7, 2013 7:45 PM in response to baltwo

Very good. I'll try it tomorrow and see what i get. Somebody else had recommended the same command (https://discussions.apple.com/thread/4280176?start=0&tstart=0) except they show the command like this:

kill -9 160

Is there a difference?

I'll let you know how it goes. Thank you!!

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Answer 6

baltwo

Level 9

62,362 points

Mar 7, 2013 10:24 PM in response to Paul Williams3

The -9 option bypasses any constraints. From man kill

-9 = KILL (non-catchable, non-ignorable kill)

BTW, FWIW, that someone else were me. 😉

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Answer 7

Mar 8, 2013 8:52 AM in response to baltwo

I didn't even notice it was you. LOL! I will try this later when i get home. Thank you!! 🙂

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Answer 8

Mar 8, 2013 4:17 PM in response to baltwo

I tried the kill command with mixed results.

As soon as i killed the PID i would run "lsof /Volumes/MyDrive" and another PID would show up. I kept killing PIDs and more would keep popping up. I did manage to kill it long enough to run disk utility successfully, but i sure wish i knew what process is playing whack-a-mole with me. Any thoughts?

Paul

A small piece of my terminal inputs:

* * * * * * *

My-MacBook-Pro:~ myname$ lsof /Volumes/MyDrive

COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME

UserEvent 800 myname 8r DIR 1,2 40256 137 /Volumes/MyDrive/Scanned

UserEvent 800 myname 9r DIR 1,2 1496 2 /Volumes/MyDrive

My-MacBook-Pro:~ myname$ kill 800

My-MacBook-Pro:~ myname$ lsof /Volumes/MyDrive

COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME

UserEvent 807 myname 8r DIR 1,2 40256 137 /Volumes/MyDrive/Scanned

UserEvent 807 myname 9r DIR 1,2 1496 2 /Volumes/MyDrive

My-MacBook-Pro:~ myname$ kill 807

My-MacBook-Pro:~ myname$ lsof /Volumes/MyDrive

COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME

UserEvent 814 myname 8r DIR 1,2 40256 137 /Volumes/MyDrive/Scanned

UserEvent 814 myname 9r DIR 1,2 1496 2 /Volumes/MyDrive

My-MacBook-Pro:~ myname$ kill 814

My-MacBook-Pro:~ myname$ lsof /Volumes/MyDrive

COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME

UserEvent 823 myname 8r DIR 1,2 40256 137 /Volumes/MyDrive/Scanned

UserEvent 823 myname 9r DIR 1,2 1496 2 /Volumes/MyDrive

My-MacBook-Pro:~ myname$ kill 823

My-MacBook-Pro:~ myname$ lsof /Volumes/MyDrive

COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME

UserEvent 830 myname 8r DIR 1,2 40256 137 /Volumes/MyDrive/Scanned

UserEvent 830 myname 9r DIR 1,2 1496 2 /Volumes/MyDrive

My-MacBook-Pro:~ myname$ kill 830

My-MacBook-Pro:~ myname$ lsof /Volumes/MyDrive

COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME

UserEvent 837 myname 8r DIR 1,2 40256 137 /Volumes/MyDrive/Scanned

UserEvent 837 myname 9r DIR 1,2 1496 2 /Volumes/MyDrive

My-MacBook-Pro:~ myname$ kill 837

My-MacBook-Pro:~ myname$ lsof /Volumes/MyDrive

COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME

UserEvent 844 myname 8r DIR 1,2 40256 137 /Volumes/MyDrive/Scanned

UserEvent 844 myname 9r DIR 1,2 1496 2 /Volumes/MyDrive

My-MacBook-Pro:~ myname$

* * * * * * *

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Answer 9

baltwo

Level 9

62,362 points

Mar 8, 2013 4:49 PM in response to Paul Williams3

No, but you might try killing the UserEventAgent via Activity Monitor and see what happens. Since the output of lsof shows directories vice files, I'm clueless. Have you disabled Spotlight on that HD's volumes?

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Answer 10

Mar 8, 2013 8:50 PM in response to baltwo

I did disable spotlight using this in terminal:

sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.metadata.mds.plist

I assume since i ran that command while the laptop was running off the external drive that this command would disengage spotlight on the external drive system.

I don't think i mentioned it above, but this external drive is a maintenance/backup drive. It's been about 2 months since it's been used. Might that have something to do with it? That's why i disengaged spotlight, i figured spotlight might want to get in there and start indexing.

I was thinking, maybe there is something else that needs to run given its been 2 months since i last used this external drice. So iwas going to start up off the external and walk away for a few hours and see if something in the system will finish what ever task it's trying to run.

Tomorrow i'll try killing the UserEventAgent as you suggest and see what happens. Is there some way to identify what process is running by the number? I assume PID is "Process Identity" or "Process Identification."

Thanks for hanging in there, i'll let you know how it goes.

🙂

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Answer 11

Mar 9, 2013 6:42 PM in response to baltwo

I tried killing UserEventAgent in Activity Monitor. I did it several times. It kept popping back up. I don't know what else to try. I'm not really buggin' out over it. I think i'm going to try letting the laptop run off the external drive for a few hours and see if the system finishes what ever it's trying to do and releases the paritiion.

Thanks for your help. If any new ideas come up let me know. I'll try just about anything.

Paul

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Answer 12

May 8, 2013 2:00 PM in response to Paul Williams3

I was working on recoving a Time Capsule error and checking the backup disk image (as per this page's recipe: http://www.macworld.com/article/1145617/timecapsulerepair.html ) when I got this same error message.

Error: Couldn't unmount disk.

I looked and found that I had opened that same disk image in the Finder as a Finder window. I closed that window, went back to Disk Utiity and clicked "Verify Disk" again, and voila! It went along on its merry way.

I hope that helps someone.

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