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So I recently removed Windows 7 from my iMac, but Bootcamp didn't let me do it. I used Disk Utility instead. The old Windows 7 partition now shows up as free space. I want to reinstall Windows 7 again on my iMac, how do I set it up? Can I use the free space again? I want to give the Windows partition a bigger size than what the free space currently holds.

Disk Utility screenshot

diskutil list command:

/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:          Apple_CoreStorage                         801.3 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS Macintosh HD           *801.0 GB   disk1
                                 Logical Volume on disk0s2
                                 54E92188-CDD5-44AE-9D58-EF6A5B69D707
                                 Unencrypted

diskutil cs list command:

CoreStorage logical volume groups (1 found)
|
+-- Logical Volume Group 25AF6969-0B3A-4C2C-BE38-29864C233F66
    =========================================================
    Name:         Macintosh HD
    Status:       Online
    Size:         801345126400 B (801.3 GB)
    Free Space:   18907136 B (18.9 MB)
    |
    +-< Physical Volume 21095CB1-4D76-44F5-B438-0B84A06AB0E8
    |   ----------------------------------------------------
    |   Index:    0
    |   Disk:     disk0s2
    |   Status:   Online
    |   Size:     801345126400 B (801.3 GB)
    |
    +-> Logical Volume Family 2DDF1B89-E73A-45E7-96CD-5FA1DC9CA275
        ----------------------------------------------------------
        Encryption Status:       Unlocked
        Encryption Type:         None
        Conversion Status:       NoConversion
        Conversion Direction:    -none-
        Has Encrypted Extents:   No
        Fully Secure:            No
        Passphrase Required:     No
        |
        +-> Logical Volume 54E92188-CDD5-44AE-9D58-EF6A5B69D707
            ---------------------------------------------------
            Disk:                  disk1
            Status:                Online
            Size (Total):          800973897728 B (801.0 GB)
            Conversion Progress:   -none-
            Revertible:            Yes (no decryption required)
            LV Name:               Macintosh HD
            Volume Name:           Macintosh HD
            Content Hint:          Apple_HFS

sudo gpt -r -vvv show -l /dev/disk0 command:

gpt show: /dev/disk0: mediasize=1000204886016; sectorsize=512; blocks=1953525168
gpt show: /dev/disk0: PMBR at sector 0
gpt show: /dev/disk0: Pri GPT at sector 1
gpt show: /dev/disk0: GPT partition: type=C12A7328-F81F-11D2-BA4B-00A0C93EC93B, start=40, size=409600
gpt show: /dev/disk0: GPT partition: type=53746F72-6167-11AA-AA11-00306543ECAC, start=409640, size=1565127200
gpt show: /dev/disk0: GPT partition: type=426F6F74-0000-11AA-AA11-00306543ECAC, start=1565536840, size=1269536
gpt show: /dev/disk0: Sec GPT at sector 1953525167
       start        size  index  contents
           0           1         PMBR
           1           1         Pri GPT header
           2          32         Pri GPT table
          34           6         
          40      409600      1  GPT part - "EFI system partition"
      409640  1565127200      2  GPT part - "Macintosh HD"
  1565536840     1269536      3  GPT part - "Recovery HD"
  1566806376   386718759         
  1953525135          32         Sec GPT table
  1953525167           1         Sec GPT header

Specs:

  • iMac11,2 3.2 GHZ
  • 1 TB HDD
  • OS X Yosemite version 10.10 (14a389)
  • EFI Boot ROM-Version IM112.0057.B01 (the latest)
0

Preparation:

  • Backup 'Macintosh HD'
  • Start another computer or smartphone and access this page here to follow the instructions.
  • Detach any external drive (especially an external Time Machine backup drive)
  • Restart to Internet Recovery Mode by pressing alt cmd R at startup.
    The prerequisites are the latest firmware update installed, either ethernet or WLAN (WPA/WPA2) and a router with DHCP activated.
    On a 50 Mbps-line it takes about 4 min (presenting a small animated globe) to boot into a recovery netboot image which usually is loaded from an apple/akamai server.

    I recommend ethernet because it's more reliable. If you are restricted to WIFI and the boot process fails, just restart your Mac until you succeed booting.

    Alternatively you may start from a bootable installer thumb drive (Mavericks or Yosemite) or a thumb drive containing a full system (Mavericks or Yosemite).

Revert CoreStorage Volume

  • Check the volume 'Macintosh HD' with Disk Utility and repair it if necessary. If the volume is corrupted beyond any repair consider a reinstall of Mac OS X.
  • If the volume is OK quit Disk Utility
  • Open Terminal from the menubar (Utilities/Terminal) and enter diskutil cs list. The output will be this:

    CoreStorage logical volume groups (1 found)
    |
    +-- Logical Volume Group 25AF6969-0B3A-4C2C-BE38-29864C233F66
        =========================================================
        Name:         Macintosh HD
        Status:       Online
        Size:         801345126400 B (801.3 GB)
        Free Space:   18907136 B (18.9 MB)
        |
        +-< Physical Volume 21095CB1-4D76-44F5-B438-0B84A06AB0E8
        |   ----------------------------------------------------
        |   Index:    0
        |   Disk:     disk0s2
        |   Status:   Online
        |   Size:     801345126400 B (801.3 GB)
        |
        +-> Logical Volume Family 2DDF1B89-E73A-45E7-96CD-5FA1DC9CA275
            ----------------------------------------------------------
            Encryption Status:       Unlocked
            Encryption Type:         None
            Conversion Status:       NoConversion
            Conversion Direction:    -none-
            Has Encrypted Extents:   No
            Fully Secure:            No
            Passphrase Required:     No
            |
            +-> Logical Volume 54E92188-CDD5-44AE-9D58-EF6A5B69D707
                ---------------------------------------------------
                Disk:                  disk1
                Status:                Online
                Size (Total):          800973897728 B (801.0 GB)
                Conversion Progress:   -none-
                Revertible:            Yes (no decryption required)
                LV Name:               Macintosh HD
                Volume Name:           Macintosh HD
                Content Hint:          Apple_HFS
    
  • Copy the UUID of the Logical Volume (lvUUID). It's the fourth listed.
  • Your Logical Volume is revertible, so enter:
    diskutil coreStorage revert lvUUID to revert your CoreStorage Volume to a standard volume. In your case this is:
    diskutil coreStorage revert 54E92188-CDD5-44AE-9D58-EF6A5B69D707
    This will take a few seconds.
  • After a successfull conversion enter 'exit' and quit Terminal.
  • Open 'Disk Utility', hightlight the volume 'Macintosh HD' and check it for errors
  • Highlight the HDD and expand the volume 'Macintosh HD' to the full possible size (~1 TB)
  • Quit 'Disk Utility' and reboot to your standard boot volume ('Macintosh HD')
  • Thank you so much! I don't have time to try it right now, but I will let you know when I successfully performed it. – Deuce55 Jan 30 '15 at 16:10
  • @Deuce55 Give me a comment if it doesn't work. The solution worked several times for me though. – klanomath Jan 30 '15 at 16:13
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Update 3) (I deleted Update 2)

I am glad, klanomath posted his answer. For me post, I would have to plagiarize his work.

Deuce55 you can ignore this update. It is directed at anyone interest in recovery partitions.

There are three types of OS X recovery partitions. They are either internal, external or internet based. Each type has its pros and cons. Internet recovery is the most reliable, but for my old 2007 iMac this is not available. For the 2011 iMac, it takes 33 minutes at my Internet Connection Speed of 2.3 Mbps. If you use internet recovery to do a clean install of OS X, you get the version of OS X that the computer was shipped with. This is not a problem if your computer is new, but later you will have to visit the App Store to get the last purchased version. If you have to do that, then I no longer consider the install to be clean.

An external recovery partion is usallly stored on a thumb (flash) drive. Using a thumb drive, for me, is much faster than the internet. You do have to download the “OS X Recovery Disk Assistant v1.0” application to create the thumb drive, but that is a minor inconvenience. Like Internet Recovery, it is reliable assuming you refresh the thumb drive after each major OS X upgrade. When used to do a clean install, you get the verion of OS X that was installed when the thumb drive was created. So if your OS X is current, then the clean install will also be current. The disadvantage with thumb drives is the “OS X Recovery Disk Assistant v1.0” is “not compatible with a disk that is using CoreStorage, including any disk larger than 2.2TB, any disk with FileVault 2 enabled, and all Fusion drives.” See System Requirements.

Finally, there are the hidden recovery partiton(s) on the internal drives. For most users, there is only one internal drive and therefore only one recovery partition. For Fusion drives there appears to be two. Booting by using these partitions is probably the fastest. Clean installs result in the installation of the same OS X version, which is good. But consider the bad. First they can be corrupted. If your drive physically fails and you replace the drive, then you have lost the use of the recovery partition. If you delete the OS X boot partition, often the recovery partition is also deleted. Finally, if you boot using the internal recovery partition(s), you can not unmount /dev/disk0.


@Deuce55: Update 1: A recovery partition is a small partition that you can boot to. It is used to repair or reinstall software. It can exist on your internal hard drive, on an external thumb drive or on the internet. The internet or thumb (flash) drive are the preferred choices. If you have one on your internal hard drive, it is not normally shown in the Disk Utility application. To use the internet, you have to have the latest Firmware update installed. See Computers that can be upgraded to use OS X Internet Recovery

Any chance you would be willing to try posting the output from the commands I asked for?

Also, do you have a thumb (flash) drive that you can reuse? If so what size?

And, do you have another computer available to communicate with while this computer is in recover mode?

Yes, you will probably what to back up your OS X partition to an external disk before proceeding. Have you ever created a .dmg image using the Disk Utility?


It looks like you are using Core Storage. If you are, then what bjb is telling you to do may not work. The resident expert on this subject is klanomath. I would recommend one of his solutions but first could you answer some questions. This would help me determine what link to create.

What version of OS X?

What version of Windows?

Do you have a fusion drive?

What is model identifier or Model/Year of your Apple?

Are you using Time Machine or other method of backup.?

If you still have your recovery partitions, do you care if you lose them?

Could you enter the following commands in a terminal application window and post the output.

diskutil list
disktuil cs list
sudo gpt -r -vvv show -l /dev/disk0

The last one will ask for your login password. This is normal. None of these commands change your computer. They just show your current disk setup.

  • The version of OS X is Yosemite version 10.10 (14a389. I am going to use Windows 7. I do not own/have a fusion drive. My iMac is from mid 2010 (21.5-inch). I am not using an external drive, but I will purchase one as it is needed in the process. I do not know what you mean with recovery partitions. – Deuce55 Jan 30 '15 at 11:34
  • I am willing to post the output down here, but I can't due to the character limit. You want me to post it in multiple comments? – Deuce55 Jan 30 '15 at 11:48
  • @Deuce55, Edit your question and post the output there. Don't worry about the format, I can clean that up for you. – David Anderson Jan 30 '15 at 12:29
  • 1
    @DavidAnderson That's your answer ;-). Boot to internet recovery -> Terminal: diskutil coreStorage revert lvUUID (because it's a revertible logical volume!) -> Disk Utility: Expand partition -> reboot -> done – klanomath Jan 30 '15 at 13:23
  • @DavidAnderson I have an 8GB USB stick. I have multiple computers I can communicate with, so that wouldn't be a problem. And sadly I never created a .dmg image. – Deuce55 Jan 30 '15 at 13:40
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If I remember correctly, if the partition type is GUID then you should be able to resize by just dragging the line that divides your partitions. You might need to delete the empty space partition first by clicking on it and hitting the '-' button, but then you should be able to drag the active partition to whatever size you want. Afterwards, you can '+' the partition back and format it for Bootcamp.

I haven't done this in a while, but from what I remember the only requirement was that you needed to have the GUID partition type for this to work. Otherwise, you'd have to reformat the entire drive. The disk utility program should attempt to relocate the blocks that were in the space that you're now moving to your bootcamp partition.

  • Thank you for your reply! There is nothing to remove. However, I can actually add something to it. Should I just click the '+'-button and set the structure to 'Mac OS extended (journaled)'? – Deuce55 Jan 29 '15 at 13:29
  • @Deuce55, you're trying to shrink the existing partition to make more room for Windows, right? If you have the GUID partition scheme for the drive, then you should be able to just resize the divider between the partitions providing you have enough free space on the currently-in-use parition since it has to shuffle things around. If that doesn't work, you could try creating a partition in the empty space and see if that makes it resizable. – bjb Jan 29 '15 at 17:41
  • creating a partition in the empty space doesn't seem to work. Closing Disk Utility or switching tabs makes the new partition disappear. – Deuce55 Jan 30 '15 at 11:47
  • @Deuce55, I would not experiment just yet. I am currently trying to determine if you have the current firmware installed. Can you goto to "About this Mac" menu and select the "System report" button. Under Hardware Overview look for "Boot ROM Version. Please post the value shown on the right. – David Anderson Jan 30 '15 at 12:02
  • @DavidAnderson, the following value shows up: IM112.0057.B01 – Deuce55 Jan 30 '15 at 13:18

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