We purchased a new FireWire-connected hard disk drive case yesterday. We now have four external drive cases. We notice that some people are interested in knowing whether it’s possible to install Mac OS on a particular external hard disk drive. If it’s a USB-powered disk drive, the answer is flatly no. So one necessary (but not sufficient) qualification for the drive to be used as Mac OS startup drive is having a FireWire connection port.

Screenshot 01 – Source: MacHouse

Screenshot 02 – Source: MacHouse

So we’ve tried installing Mac OS X 10.5 on this new hard disk drive case, which has both FireWire and USB ports. It doesn’t take a 15-year Mac veteran to figure out that the first step is to insert an OS startup DVD to the computer. Then I need to use the Startup Disk pane to select the installation disc and click on the restart button. (See Screenshot 01.) The target drive is named ‘160 GB.’ When the iMac starts up on the installation disc, I see the ‘Select a Destination’ screen. We know that Mac OS can only be installed on a volume with a downward-looking, yellow-green arrow. Looking at the computer screen, it doesn’t look like we can install Mac OS X 10.5 on 160 GB. (See Screenshot 02.)   Continue reading →