I installed Mountain Lion on my external HDD a while ago, just to test it and the new XCode out, but without realizing what I was doing, I adopted it as my main OS. Now I am stuck having my external HDD plugged in all the time. I was wondering if there is some way to port my OS to my internal HDD.

Preferably, I would also like to keep my internal OS on my external HDD. I have a partition that is big enough to hold my entire internal OS.


Well, I did find out my own answer. Basically, in the disk utility application, there is the restore option. You will need to be running on the recovery disk partition in order to do this.

In disk utility, I created a partition for my internal OS on my external HDD and I restored my OS to that partition. Then I did the same thing for my Mountain Lion OS and restored it to my main HDD (internal). It worked great, but certain applications didn't get passed over properly, for some reason (XCode included).


Go to System Preferences. Click on Startup Disk. And choose your internal hard drive from the list. I have not used Mountain Lion, but I imagine this part of the preferences hasn't changed.

To get your internal OS onto the external hard drive, use a disk cloning utility such as Carbon Copy Cloner, Get Backup, or Superduper. But before you do it, make sure the destination partition is formatted as HFS (Mac OS) otherwise it won't be bootable.

  • Okay. But how would I get my external drive onto my internal drive?
    – RileyE
    Aug 19 '12 at 20:51

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