Apparently the original aluminum iMac does not boot from Firewire. No Mac from before 2008 apparently boots from Firewire. They only boot from USB.
I learned this as usual the long way around instead of reading the manual. So the 6 year old iMac’s hard drive finally is going bad. Now in any normal computer I’d just replace it. However looking at the process for the iMac I decided against replacing the internal hard drive. You see, Macs can boot from external hard drives, the iMac is really just for watching movies now, and there’s no need for super fast hard drive access anymore. Plus I really don’t want to break a perfectly fine computer to replace the hard drive. So an external hard drive seemed a fine replacement for the internal drive.
I have experience in this after all. I’ve 2 2.5in hard drives I have clones of the MacBook and iMac on. So I wasn’t too concerned the iMac was failing as I have good backups and we could use the 2.5 in drive to keep it running. Those connect via USB and work just fine. The iMac in the course of the last few days has run on its failing internal drive, the external copy of the iMac, and the external copy of the MacBook. That is some pretty sweet flexibility that you can just swap the computer so easily by changing the hard drive. Even though they seem expensive I think I’ve convinced myself of the goodness of Macs again here. Just a quick purousal seems to show that Linux and Windows can’t do this as easily as having a hard drive, restarting with the option key pressed and choosing any of the connected system hard drives to boot from. Correct me if I’m wrong but there are some bits that are still easier on a Mac (other than just replacing the drive…).
The 2.5in plastic drive is more a backup though, didn’t want to run the computer forever on that. So I ordered a nice 3.5in drive in an aluminum case. It seems like it should last longer with the better heat dissipation with aluminum. So I ordered a nice Other World Computing drive and it came right off. The plan was to use the Firewire 800 connection as that’d be fast than the USB2 one. So after a couple of days trying to figure out why the iMac wouldn’t boot from the new harddrive I decided I should look in the little book that came with the drive. Ack! Macs before 2008 cannot boot from Firewire! Good thing the drive also has a USB connection! Now we’re running on that and it’s working fine.