Cannot change Hard Drive to GUID

Discussion in 'macOS' started by Octavia, Oct 4, 2009.

  1. Octavia macrumors newbie

    Oct 4, 2009
    I am trying to install the Snow Leopard upgrade on my MacBook (Mac OS 10.5 Leopard), and I can't seem to do it because it tells me to change my partition scheme table to GUID. I went into disk utilities and clicked on the "partition" tab, but I can't click on the "options" button. I cannot erase my hard disk either. What could be the problem?

    Just in case this is important: I changed my 160GB original HD to one of those WD passport HDs. So now my internal HD is the 500GB WD passport HD.

    Help Please! I already backed up my HD onto an external HD using Time Machine, but I cannot erase my internal (WD) HD!
  2. Peace macrumors Core


    Apr 1, 2005
    Space--The ONLY Frontier
    If you could supply a screenshot of your disk utility open with the HD showing it would help.
  3. tomekinc macrumors newbie

    Jul 16, 2007
    I am having this exact same problem. I upgraded to the Seagate 500 GB HD and tried doing some upgrades today to find out my partition scheme is the Apple Partition and not GUID.

    I cannot erase or partition, the buttons are greyed out and simply cannot be done. I tried booting from the CD but I cannot because it is the Apple partition sheme.

    This is like a catch 22, how do I erase this and reinstall to GUID?
  4. misterredman macrumors 6502a


    Oct 3, 2007
    What cd did you try to boot from? You should be able to boot from the CD no matter what the partition scheme of the HD is.
  5. sys0p macrumors member

    Feb 1, 2007
    erase all partitions (second next to first aid) on the Harddrive level in diskutility

    then recreate a new one should allow you to set the optiones you want
  6. quidoh macrumors newbie

    Oct 24, 2009
    I had exactly the same problem. If you have a TimeMachine backup this is what works to change to GUID partition without losing anything.

    1. Boot from the Snow Leopard Install DVD by holding the C key while booting
    2. Instead of installing Snow Leopard, choose Utilities > Disk Utility from the menu and choose tab Partition.
    3. Set 1 or more partitions and choose GUID. This wil erase everything and create new partition(s). You will get everything back later from your Time Machine backup.
    4. Now Install Snow Leopard
    5. After installing you get to a screen that says "Do You Already Own a Mac?". Choose the option to transfer information from a Time Machine backup (make sure the HD that contains the TM backup is connected). Choose the TM backup and presto, your original files and settings will be put back.
  7. pcs are junk macrumors 65816

    Sep 28, 2009
    u cant just go to the partition tab, theres more to it. click on the thing that has selections, like when u click it a list comes up, ok so its called Volume Scheme, the default one should be current, click on that, then if u are just partitioning it for 1 os, or if u are adding snow leopard to another half of ur drive, for upgrading click 1 partition, for both leopard and sl, click 2 partition, then click options, then click the guid thing, then you should be all set.
  8. gr8tfly macrumors 603


    Oct 29, 2006
    ~119W 34N
    As pcs are junk said -

    The "Options..." button will be grayed out unless you change the Volume Scheme from Current to a specific number of partitions (probably 1).

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