Faisal600

Q: Couldn't unmount disk

Heveryone

My iMac desktop for some weird reason is getting super slow. I backed up all my data and I want to restore factory settings but I keep getting this message " couldn't unmount disk"

Photo attached

 

 

http://imgur.com/Y6NFgbl

iMac, iOS 8.3

Posted on May 20, 2015 2:21 PM

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Q: Couldn't unmount disk

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  • by Kappy,

    Kappy Kappy May 20, 2015 2:27 PM in response to Faisal600
    Level 10 (271,291 points)
    Desktops
    May 20, 2015 2:27 PM in response to Faisal600

    If your model is from 2011 or later and did not come with Software Restore DVDs:

     

    Install or Reinstall OS X from Scratch

     

    Be sure you backup your files to an external drive or second internal drive because the following procedure will remove everything from the hard drive.

     

    Boot to the Recovery HD:

     

    Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.

     

    Erase the hard drive:

     

      1. Select Disk Utility from the main menu and click on the Continue button.

     

      2. After DU loads select your startup volume (usually Macintosh HD) from the

          left side list. Click on the Erase tab in the DU main window.

     

      3. Set the format type to Mac OS Extended (Journaled.) Optionally, click on

          the Security button and set the Zero Data option to one-pass. Click on

          the Erase button and wait until the process has completed.

     

      4. Quit DU and return to the main menu.

     

    Reinstall OS X: Select Reinstall OS X and click on the Install button.

     

    Note: You will need an active Internet connection. I suggest using Ethernet if possible

               because it is three times faster than wireless.

     

    This should install the version of OS X that you had installed.

     

    If you are running Snow Leopard or earlier:

     

    Clean Install of Snow Leopard

     

    Be sure to make a backup first because the following procedure will erase

    the drive and everything on it.

     

         1. Boot the computer using the Snow Leopard Installer Disc or the Disc 1 that came

             with your computer.  Insert the disc into the optical drive and restart the computer.

             After the chime press and hold down the  "C" key.  Release the key when you see

             a small spinning gear appear below the dark gray Apple logo.

     

         2. After the installer loads select your language and click on the Continue

             button. When the menu bar appears select Disk Utility from the Utilities menu.

             After DU loads select the hard drive entry from the left side list (mfgr.'s ID and drive

             size.)  Click on the Partition tab in the DU main window.  Set the number of

             partitions to one (1) from the Partitions drop down menu, click on Options button

             and select GUID, click on OK, then set the format type to MacOS Extended

             (Journaled, if supported), then click on the Apply button.

     

         3. When the formatting has completed quit DU and return to the installer.  Proceed

             with the OS X installation and follow the directions included with the installer.

     

         4. When the installation has completed your computer will Restart into the Setup

             Assistant. After you finish Setup Assistant will complete the installation after which

             you will be running a fresh install of OS X.  You can now begin the update process

             by opening Software Update and installing all recommended updates to bring your

             installation current.

     

         5. If you are planning to sell or give your computer away, then do the following:

     

            After you reformat your hard drive and reinstall OS X, the computer restarts to a

            Welcome screen and asks you to choose a country or region. If you want to leave

            the Mac in an out-of-box state, don't continue with the setup of your system. Instead,

            press Command-Q to shut down the Mac. When the new owner turns on the Mac,

            the Setup Assistant will guide them through the setup process.

     

    Download and install Mac OS X 10.6.8 Update Combo v1.1.

  • by Faisal600,

    Faisal600 Faisal600 May 21, 2015 12:28 AM in response to Kappy
    Level 1 (0 points)
    May 21, 2015 12:28 AM in response to Kappy

    I did exactly what you suggested and I got the same result with the same message.

  • by Kappy,

    Kappy Kappy May 21, 2015 12:52 PM in response to Faisal600
    Level 10 (271,291 points)
    Desktops
    May 21, 2015 12:52 PM in response to Faisal600

    You have the same problem even after installing from scratch? Then you may have a faulty drive.

  • by Faisal600,

    Faisal600 Faisal600 May 22, 2015 1:23 PM in response to Kappy
    Level 1 (0 points)
    May 22, 2015 1:23 PM in response to Kappy

    I don't have the recovery disks so I couldn't do your second recommendation regarding the snow leopard. But I tried to erase the disk using disk utility and that have failed .

  • by Kappy,

    Kappy Kappy May 22, 2015 1:32 PM in response to Faisal600
    Level 10 (271,291 points)
    Desktops
    May 22, 2015 1:32 PM in response to Faisal600

    You cannot erase a startup drive. You must boot from an installer disc or from an external HDD or from another computer connected using Target Disk Mode.

     

    What version of OS X do you have installed? Exactly what Mac model do you have?

  • by Faisal600,

    Faisal600 Faisal600 May 23, 2015 1:43 AM in response to Kappy
    Level 1 (0 points)
    May 23, 2015 1:43 AM in response to Kappy

    OS X Yosemite

    Version 10.1Ima

    iMac 27 inch late 2009

  • by Kappy,

    Kappy Kappy May 23, 2015 1:15 PM in response to Faisal600
    Level 10 (271,291 points)
    Desktops
    May 23, 2015 1:15 PM in response to Faisal600

    Boot Using Command+R keys:

     

      1. Restart the computer.

      2. Immediately after the chime press and hold down the

          "COMMAND" and the "R" keys together.

      3. Release the keys when the Utilities Menu appears.

  • by Faisal600,

    Faisal600 Faisal600 May 23, 2015 5:07 PM in response to Kappy
    Level 1 (0 points)
    May 23, 2015 5:07 PM in response to Kappy

    Kappy,

    I truly appreciate the help. I tried to erase the disk through disk utility but it failed. This is why I'm posting  my question here. I also don't have the recovery disk. Is there another way to resolve this issue.

  • by Kappy,

    Kappy Kappy May 23, 2015 5:35 PM in response to Faisal600
    Level 10 (271,291 points)
    Desktops
    May 23, 2015 5:35 PM in response to Faisal600

    You are pretty much stuck. If you cannot boot to a Recovery HD, then you cannot perform any normal Disk Utility repairs or reinstall Yosemite. That means you must start from the beginning by installing the version of Snow Leopard that was originally installed or purchase the Snow Leopard Retail DVD: You can purchase Snow Leopard through the Apple Store: Mac OS X 10.6 Snow Leopard - Apple Store (U.S.). The price is $19.99 plus tax. You will be sent physical media by mail after placing your order. After you install Snow Leopard you will have to download and install the Mac OS X 10.6.8 Update Combo v1.1 to update Snow Leopard to 10.6.8 and give you access to the App Store.

     

    Unless you have access to another Mac with Snow Leopard 10.6.3 or later that you can restore to your computer via Target Disk Mode, there is nothing you can do until you get the Snow Leopard DVD.