Cannot resize / delete partition

Discussion in 'Mac Basics and Help' started by sebifastmr, Aug 4, 2014.

  1. sebifastmr macrumors newbie

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    Aug 4, 2014
    #1
    Hey

    Many people out there seem to have problems with adjusting their partitions but in none of the threads I could find an answer to the problem occurring on my Mac. I added another partition to my Mac and left it as free space. It eventually turned out that I don't need the free space and that I want to resize the old OS X partition so that it's bigger. When I try to make it bigger in Disk Utility I get the error 'couldn't unmount disk'. I booted into recovery and deleted the everything on the MacintoshHD partition hoping I would be able to delete it and set up a new one, but the same error shows up again. I tried everything I could find to unmount it, even the force unmount command in Terminal that should delete everything on the drive. But also this gave me the unmounting failed error. Can somebody tell me how I get my MacintoshHD partition back to its original size?

    Cheerio

    sebifastmr
     
  2. Weaselboy Moderator

    Weaselboy

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    #2
    Do you happen to have Filevault on? Confirm you are on Mavericks and not Yosemite?

    Enter "diskutil list" (without the quotes) in Terminal and tell me what it says.
     
  3. sebifastmr thread starter macrumors newbie

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    #3
    I'running Mavericks only.

    Don't think FileVault is on, how can I switch it off in recovery?
     
  4. Weaselboy Moderator

    Weaselboy

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    #4
    Post up the results of that diskutil command and I can be of more help.
     
  5. sebifastmr thread starter macrumors newbie

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  6. sebifastmr thread starter macrumors newbie

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    #6
    Here's what the command says
     

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  7. sebifastmr thread starter macrumors newbie

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  8. sebifastmr thread starter macrumors newbie

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    #8
    It's the partition that has the size of 57 GB I'm trying to alter...
     
  9. Weaselboy Moderator

    Weaselboy

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    #9
    See all those other disk5 disk6 things on there... that is concerning and sometimes means a bad drive, or less commonly a bard drive cable.

    I assume here you have a Time Machine backup and don't mind wiping the whole drive??

    Try a command-option-r (all three keys are once) boot to Internet recovery. Join your wifi network then a globe will spin while the recovery utility downloads. This is not the one you get with a command-r boot.

    Once the utility downloads launch Disk Util and see what a repair disk tells you? Then try and resize from there. If that fails as a last resort select the drive brand name itself at the very top above Macintosh HD and erase the entire drive to Mac OS Extended (Journaled) then restore from the TM disk.
     
  10. sebifastmr thread starter macrumors newbie

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    Aug 4, 2014
    #10
    Thanks for the quick reply. I've already tried the latter, namely going to disk utility and try the erase button of the physical drive (brand name as the name of the disk). This unfortunately resulted in the same error...
     
  11. Weaselboy Moderator

    Weaselboy

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    #11
    Yes... but did you try it from Internet recovery as opposed to regular command-r recovery. When in command-r recovery you are actually running off the 650MB recovery partition on the disk and limits what you can do because the disk is mounted. By running Internet recovery the utility downloads and runs in memory so you can better manipulate the disk partitions as it is not mounted.
     
  12. HarryPot macrumors 6502a

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    Sep 5, 2009
    #12
    I just had the same problem as you.

    I created a new partition for Yosemite, in addition from the main partition with Mavericks.

    After deciding to erase the Yosemite partition and return to just having one with Mavericks, I received the same error "can't unmount disk...".

    I tried everything I could find on the web, and nothing worked. Eventually I messed so much with Terminal commands that I ended with a completely dysfunctional hard drive.:(

    My final solution was to boot from an external bootable drive, enter Disk Utility, Erase the internal disk and restore from a Time Machine backup.
     
  13. sebifastmr thread starter macrumors newbie

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    #13
    @weaselboy

    internet recovery seems to be unavailable for my Mac (2009)

    http://support.apple.com/kb/HT4904

    @harry

    does your method work even when erasing the internal drive is impossible while booted into recovery (without USB drive)?
     
  14. HarryPot macrumors 6502a

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    #14
    In theory it should work, in the past I've been able to enter the recovery partition and Erase my internal drive to achieve a clean install. But this last time making this displayed the same error of "can't unmount disk...".

    I suppose that the way I created the additional partition, or the commands I entered in Terminal, damaged something in the drive.
     
  15. Weaselboy Moderator

    Weaselboy

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    #15
    Yeah.. crap. Too old.

    You can still boot and run it yes? Use this Apple utility and a 1GB or larger USB key to make a recovery key, then option key boot to the USB key and from there try what I said.

    We gotta get you booted off something other than the internal drive.

    Do you happen to have a Time Machine backup? You can also option key boot to that and it will have recovery screen where you can do this.
     
  16. sebifastmr thread starter macrumors newbie

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    Aug 4, 2014
    #16
    Solved

    Thanks so much guys, the recovery stick seems to have solved the problem. Was able to resize the partition to its maximum size and reinstalled 10.9. I really like the forum!
     

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