Why does my Mac formatted hard drive say it is read only?

Aaron November 30, 2011
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I have a MacBook installed with 10.6.3 and I recently acquired a WD hard drive for it. Now I had the person who sold it to me format it for a Mac.

My son has taken it out while the hard drive was running. Now it says the hard drive is read only and Disk Utility will not let me erase or reformat the hard drive. I do not care about the things on the hard drive as I can acquire them again, but it would be nice to have a new hard drive that works. Now when I plug the hard drive in it says it is not able to mount the drive. So what can I do?

    December 1, 2011 at 5:32 am

    Hello, I guess your external drive got corrupted when it was disconnected from mac.  If the disk utilities for your mac are not able to format the disk, you could download the gparted live cd and run it.  Mac uses the HFS.  If you are using the external only for mac, formatted with the HFS extension.  If you are trying to use it in mac and windows you could formatted with FAT32.  Here is the link for gparted:


    You can download the cd or usb version.  The link will also show you the instructions.  Hope it helps

  2. Anonymous
    November 30, 2011 at 10:37 pm

    TRy this method

    you can try to plug the hard drive on Windows and format there to FAT32 then replug to MAC and reformat.