I used my external hard drive to put on a DMG file for a program and now my external hard drive is acting as a CD.
I wanted to erase the DMG so I could use my external hard drive to put my files on it and use as back up but when I go into disk utilities and click erase it says "Cannot unmount disk."
I'm so confused right now, any help is appreciated.
MacBook Pro, Mac OS X (10.6)
I finally found the answer!!
If anyone else is wondering how to erase your hard drive after mounting a DMG file on it to use it as an installation disk here's how you do it!
1.Eject the disk from your desktop by clicking on it and then pressing command()+E. DO NOT pull out the cord connecting the external HDD to your computer.
2.Go in to Disk Utility, select the external HD on the left. Note that you cannot select the actual partition, just the HD with the partition.
3.Click on the Erase tab at the top, and proceed with erasing the disk. You may now do whatever you want with it.
PLEASE NOTE THAT FOLLOWING THE ABOVE INSTRUCTIONS WILL DELETE EVERYTHING ON YOUR EXTERNAL HARD DRIVE.
Hello:
I have never put a dmg file on an external disk (why do that, if I may ask?).
In any event, the only guidance I could find was this article…but it seems to address dmg files on the internal HD:
http://support.apple.com/kb/TA20701
Barry
I am so miffed. I had a similar thing happen last night and intend to make my 2:30 appointment at the genius bar. I will back in touch.
It is such a stuck situation.
If you find out how to fix it let me know please! 🙂
thx I used it and works fine
Can't erase my external hard drive
