[doconmac]

PROBLEM

I recently purchased a WD MyBook Home 1TB for backups.
It is partitioned into 2, and has a bootable SuperDuper clone on one and Time Machine on the other. It is connected with a FW 800-400 cable as the iMac only has FW 800 and the WD drive FW 400.
(I know this is dodgy as if it fails I lose both but I also have a 160 GB Verbatim USB 2 drive which also runs SuperDuper every night.) Call me paranoid...

All the backups work fast and smoothly, Time machine functions perfectly. If I choose the WD HD SuperDuper Volume as Startup volume in System Preferences, it boots just fine so I can run repairs on the iMac or restore files.

However, if I do a cold start holding the Option key, despite all the volumes appearing in Startup Manager, the Mac will NOT boot from the SuperDuper volume when chosen. All I get is the grey screen and Apple logo and then nothing.

If, however I connect a USB2 cable to the WD HD, it will boot from Startup Manager as well as by choosing a volume in Startup Disk in System Preferences.!

The WD website states that this HD will boot with FW or USB2 with an Intel Mac. I have updated it's firmware, no difference.

SOLUTION:

Hi Dave,

I came across a post which suggested that if you don't unmount ext HDs before shutdown, it can do bad things to them as startup drives. In fact I always just shutdown without unmounting the drive volumes.
So, I unmounted the WD HD and then shut down as usual.
I then started with Option key and entered Startup Manager, chose the SD volume and it booted perfectly!

Then I noticed that when I shutdown the Mac from the Apple Menu, after it shuts down, the MyBook also turns off, and the light goes off, whereas my LaCie drives have always remained on in standby mode with the blue light still on.

So this time, I shut down,
Then I pressed the power button on the MyBook and it turned on.
Then I entered Startup Manager, chose SD volume and guess what, it booted perfectly.

The reason I am letting you know this is so that if other people have the same problem with SD booting from WD HDs
you will know what to tell them.

So if my Mac ever refuses to start from it's internal drive, I can now boot from the WD HD to access my SD Clone.
I can then use DiskWarrior to repair the internal drive and/or recover files to a DVD.
Now I am a happy camper and I can continue to use Firewire as you recommend, and I prefer!


iMac Early 2009 24" 2.66GHz 4GB RAM OS 10.5.6