[How To] Boot to Dead Disk

[bobw]

From Macosxhints.com;

If your Mac is booting to a folder with a question mark instead of Mac OS X, and happens that you do not have a System CD with you from which to boot and fix your startup disk, here is a trick that may bring it back to normal. It should also work for most new Macs. Boot to Open Firmware by pressing Alt+Command+O+F on boot. At the prompt, type the following two lines:

set-defaults [hit Enter]
boot hd:,SystemLibraryCoreServicesBootX [hit Enter]

Hopefully your Mac will boot to OS X or if the trick doesn't work, to a white screen with an error signal instead of the Apple logo, just switch off the box and try the commands again. Remember to re-set your startup disk to the Mac OS X folder in the Preferences -> Startup Disk after you get running again!

If this trick doesn't make your Mac come back, you may want to go and read this document,

http://www.bombich.com/mactips/openfirmware.html

and additionally this info on Open Firmware by Apple

http://developer.apple.com/technotes/tn/tn1061.html

Finally, this one is a quick info page for OpenFirmware, very clear and useful.

http://www.firmworks.com/QuickRef.html

 

[fryke]

I hope I'll remember this one when I'm presented with a question mark the next time. No, wait: I hope I don't _have to_ remember it. ;-) It's been a while since my last question mark...

 

[ksv]

If your Mac is booting to a folder with a question mark instead of Mac OS X, and happens that you do not have a System CD with you from which to boot and fix your startup disk, here is a trick that may bring it back to normal.

Does that just happen by itself? I can only recall having that happen once with Mac OS X, when I had set some hard drive jumpers incorrectly.

 

[fryke]

Well, it can happen if your boot-partition goes dead or at least "difficult to read from". ;-) I had this happen sometimes with using different FW drives (one with a system, one without). Set the FW drive (with system) as the boot-volume and then shutdown your Mac. Switch FW drives. Start up your Mac and: Voilà. Can't boot from selected volume.
Another scenario: Boot from Partition 1. Set Partition 2 as boot volume. Format Partition 2. Reboot.
It's not something you'd come across on a daily basis, but it can happen without removing/adding/setting jumpers on harddrives. ;-)