[Veltliner]

It's common knowledge that you can create an identical image of your hard drive on your fire wire external hard drive, and then boot from that hard drive.

But when I think of it: how does it really work IF your computer can't boot?

If my computer doesn't boot, I won't have access to my firewire drive. How would I want to do an emergency boot from that hard drive?

Solution could be: booting the computer from the installation disk (if possible), and then, somehow, delegate the duty to the fire wire external hard drive.

I'm just guessing here...

My computer runs great, but I'm really curious...

Corrections and add-ons, especially a step-by-step approach would be appreciated.

[Simon]

If you can't change the boot partition in Sys Prefs you can always hold alt/opt at boot time. That will bring up the boot partition selector. Of course you could also boot from an install DVD and use that to change the boot partition setting, but the alt/opt method is certainly easier and a whole lot faster.

IIRC there's also a key combo to prevent the Mac from booting off the default boot partition. I'm not sure anymore, but cmd-alt/opt-shift-delete maybe?

[greene_hornette]

When you first boot up the computer, press and hold the option key - a simple GUI should appear
with a list of all volumes available to boot from.

FYI - this is the method for PPC processor -based macintosh computers, so the intel models may differ.

[Simon]

Originally Posted by greene_hornette 

FYI - this is the method for PPC processor -based macintosh computers, so the intel models may differ.

They don't. Alt/opt during boot will let you select the boot partition on PPC and Intel Macs.

[analogika]

Originally Posted by Simon 

They don't. Alt/opt during boot will let you select the boot partition on PPC and Intel Macs.

The option-key thing is the same but the boot manager is done scanning all available buses MUCH faster than on PPC systems.

[Simon]

PPC Macs aren't intended to boot from USB devices so the USBs don't need to be scanned. I'm guessing that's the reason.

[analogika]

Originally Posted by Simon 

PPC Macs aren't intended to boot from USB devices so the USBs don't need to be scanned. I'm guessing that's the reason.

I'm not sure why that would make the *Intel* machines so much FASTER at scanning, though.

[Art Vandelay]

Nope, Intel Macs don't scan the network for a NetBoot server. PowerPC Macs always scan the network for a NetBoot server. On an Intel Mac, if you want to NetBoot either boot and hold down 'N' or boot with Option held. When the Startup Manager appears, tap 'N' and it will then scan the network for NetBoot servers.

Also, EFI is much faster than Open Firmware but the reason above is the main speed difference.

[Veltliner]

Thanks to all of you for the information!