Partition issue, couldn't unmount disk (error)

What's going on here is that most of us are actually talking about different problems and solutions that will only work on some computers. It is my opinion that goldfish had the same issue as me, in that there were partitions previously to upgrading to Lion, which caused a problem during the hot partitioning of the disk when the Recovery HD was added. This problem may have been causing, or might have been separate from and only have been compounding the issue wherein we were unable to successfully get to the external Recovery HD. Our computers were refusing to boot to the external disk, and this was difficult to recognize because they are identical and it is counter-intuitive to assume that the selected boot volume was being ignored in favor of the internal disk everytime.

A lot of the offered solutions that follow fail to recognize that goldfish could not unmount the internal volumes because he was not booted to the external drive afterall. The only way around that problem was to delete the internal Recovery HD and thus preclude any possibility of booting to it.

Also, I think, but am not sure, that the suggestions to change the partition map on the live boot volume will not work if there is a hidden Recovery HD.

And no, d34dfish, that computer i had did not have a thunderbolt port, only a minidisplay port. That particular revision of the macbook air was lame.

That *****- the gap between FW and TB is a big one. I was afraid to buy anyting while it was happening and still suffered a bit since it took them forever to get the TB > FW adapter out.

Can you boot to USB image of the OS? I just created one for a client when mavericks woudln't load on it's own and it worked great. I wish I had a machine with this issue so I could play with it a bit and try to resolve it myself.

Sorry my tip didn't help!

Ok, I see a lot of the same responses to this problem. ..none of them work for me.

I have an early 2008 Macbook Pro, Intel based with OS 10.9.2 Mavericks installed.

I had some issues that prevented me from booting into safe mode, so I got in through Daemons to get my data backed up. HOWEVER, I had to back up files online because since the file corruption external drives do not show up...not in DU (launched or in Recovery mode) or in terminal.

So, I'm in Recovery mode. I have erased and chosen extended journaled for the format. My drives are just a main partition and a 37 gb time machine partition.

Under that on the left "disk 1" Main OSX.

When I try to adjust the partition, I also get the error of "Can't Unmount drive".

When I click 'repair disk' on the main partition, BDGibbs, it says that the volume is ok. When I try this for the hd, it says that it's not supported live.

I can't seem to erase, mount, adjust partitions or anything with this drive.

When I try to reinstall OSX...The only drive I can install it on is BDGibbs. It shows that the Recovery drive is locked...

But when I select "Startup Disk" from the Apple icon, it doesn't show any bootable drives.

When the OS is reinstalled, instead of restarting, it goes back to the Recovery mode main menu. When I manually restart...it boots back to Recovery mode without holding any keys. I've even hard booted and still automatically back to RM.

Please help. Again, my laptop is not recognizing external drives so that is not an option. Is there something I am missing here?

@BD_Gibbs...

I MADE A MAVERICKS USB INSTALL "THUMB DRIVE" AND BOOTED FROM IT. THEN I CHOOSE THE "THUMB DRIVE" AS THE BOOT DEVICE IN THE INSTALL SETUP. I REBOOTED...

I WAS THEN ABLE TO ERASE THE OLD OS DISC.

1: BOOT FROM USB INSTALL OR OS DVD INSTALL

2: CHOOSE THE SAME DEVICE YOU JUST BOOTED FROM AS THE STARTUP DISC.

3: REBOOT.

4: NOW YOU CAN UNMOUNT / ERASE THE OLD OS DISC.

BASICALLY... YOU ARE FORCED TO BOOT FROM AN EXTERNAL USB OR DVD IN ORDER TO CORRECT THIS.

"RECOVERY" MODE WILL NOT WORK.

TRUST ME...

JEFF

Message was edited by: SKULLYARD

Ok, I can not get a USB drive to register....

But after actually speaking with Apple... you can start from Internet Recovery Mode. Command + Option + R. It will be the same as booting from a recovery drive on an external.

I'm having the same issue with Mavericks as the original poster. This is clearly a bug, so I'm not sure why Linc's responses to goldish are so combative.

The REASON we are getting an error is that Disk Utility is attempting to unmount a volume that it has already unmounted; Disk Utility in Recovery unmounts the volume prior to the "Checking catalog file" step. (This is a trivial check in Disk Utility's code to ensure that the unmount(2) system call's errno is not EINVAL. Or, alternatively, you could ensure that the code doesn't try to unmount the volume twice in the first place, but that might require actual work.)

Here are the steps to reproduce the issue, assuming you have a 10.9 system and a HDD split into regular and Boot Camp partitions.

1. Boot into the recovery partition. I held "option" while powering on and chose the Recovery volume.
2. Launch Disk Utility.
3. Select the main HDD, then the Partition tab.
4. Select the Boot Camp partition and erase it with the "-" button.
5. Hit "Apply." This should finish successfully.
6. Resize the remaining volume to fill up all remaining space.
7. Hit "Apply" again.

The reason you can get this to work from within the regular boot volume is that the regular system doesn't attempt to unmount it twice. But since I'm attempting to reset my computer to zero to return it to inventory, this is a huge extra effort to reboot into the regular volume, create a user, run Disk Utility there, then reboot back into Recovery and re-install OSX a second time just to resize the disk partition.

I have had the same issue for a long time now. Partitioned Bootcamp so I could do some school work that required windows OS. I was able to delete the Bootcamp partition but to restore the full size of my main partition, nothing worked, always got the error where it could not unmount the drive. Booting into the internet recovery by starting up while holding cmd opt r, going into disk utility and then dragging down my main partition back to max worked, FINALLY, with no issues at all.

Thank you, thank you and thank you again! Here is a man that know what's he talking about! I did not however use DiskMaker X, I used the "DU" and followed your directions and it worked!!! Thanks a bunch!

Hi

For me what worked was the following:

1. Create an external boot device (bootable SD card)

Here is the link to the procedure I followed

Create a bootable installer for OS X Mavericks or Yosemite - Apple Support

2. Boot from an external device (in my case a SD card)

For shortcuts for different boot options please see the following link

Startup key combinations for Intel-based Macs - Apple Support

3. Once the system booted from the external device I went to the menu and opened "Terminal" and entered a command (found in the link below) in order to force the unmount

http://apple.stackexchange.com/questions/105673/disk-utility-wont-unmount-hd-for -formatting

4. Went to the disk utility and now I could format the partition (in my case I created a Raid1 and then formatted)

Hope it helps

All the Best

Thanks geoffist, this worked like a charm.

Goofiest solution worked for me. Background: I erased Bootcamp from my macbook pro, and then had issues repartitioning my hard drive. I was unable to get rid of the partition that the Bootcamp program occupied. I got the "Partition Failed: Couldn't Unmount Disk" message. I searched a lot of other possible solutions, but then I finally stumbled upon Geoffist's solution and it worked on my first attempt.

If none of the disk utility and external boot options are working for you try this. It worked for me after hours of forums and confusing posts. Simple and effective and now I was able to erase my disk and it mounts.

http://technology.siprep.org/fix-for-disk-erase-failed-couldnt-unmount-disk/