a) single partition 2 TB external firewire HD w/ 10.5.8 (my current StartUp Disk)

b) single partition bootable USB drive with 10.6.7 (full version / not just an "upgrade" version)

c) single partition bootable USB drive with 10.8.2 (full version / not just an "upgrade" version)

Desired Outcome: run 10.8.2 on the single partition firewire HD (item "a" above)

Constraint: the single partition firewire external HD w/ 10.5.8 (current StartUp Disk) is a 2TB drive, and it also has other (non Mac OSX related) data files on the drive that I do not want to lose. To be clear, the constraint is that I do not want to erase this drive during the upgrade process.

System Details: 2008 Intel iMac 24", 4 gig RAM, USB 2.0, broken-ass internal DVD drive, broken-ass internal HD

My Question: how best to achieve the desired outcome? If not possible, please suggest next best alternative.

My Appreciation For Your Help: sincere & immense :-)


You risk loosing your data in any upgrade. You need to backup your important data. If your data isn't backed up, you do not have your data.

I recall you need to upgrade to 10.6 so you can do an online install of 10.8. With an upgrade, the installation manager will not erase your data. I have not tried this.


  • I would just--temporarily, at least--copy those files you don't want to lose over to your machine, erase, verify + repair (run Disk Utility, and Disk Warrior if you have it) the FW HD and do a fresh install of 10.8 - then applying updates. Of course, that ignores your constraint, but drag and drop would take but minutes. And this is so much cleaner than installing over. – Zo219 Mar 20 '13 at 2:06
  • @historystamp Hi, Robert. Importance of backup - understood, thanks! As to the compliance w/ the "Constraint" (in the question), is it your understanding that if the OS to be upgraded resides on an external 2 TB HD that only has one partition, and also contains over 1 TB of personal (non-OS) files on that same partition, after upgrading the OS on that drive...the personal (non-OS) files will remain undisturbed? David – user18467 Mar 21 '13 at 7:35

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .