boot from USB external?
 

Hi -

I know there's a sticky on this, but I wanted to see if I could get some more info.

I have a new Intel MacBook running 10.5.5, and I have a Fujitsu MHV2080 SATA in a cheap USB enclosure (USB-powered). I was hoping to be able to boot from this disk, but don't seem to be able to. Yes, I partitioned with GUID formatting, and did a SuperDuper full backup copy onto it from the same machine I want to boot from. As you might gather, the disk mounts fine. The backup copy on the disk looks fine.

Then I do a restart holding down the OPTION key with the disk connected. The startup manager comes up, but the external disk isn't there!

Is this one of these deals where not quite all USB drives are bootable, and I just happen to have one that isn't. Or ... ? Do I really have to get myself a Firewire enclosure? Fortunately, this is a last-generation MacBook that has a Firewire port! Is this a SuperDuper issue, a USB issue, a disk issue, or an enclosure issue?

I gather that I may have to connect the enclosure to an external power supply. But would low power produce this symptom? As I said, it mounts fine.

Thanks,

Dan

occasionally...
 

Occasionally, I when I try to boot my G5 iMac from my FW LaCie, it doesn't show up. I then have to power down and try it again before it works. I now let the external spin up for a few minutes before I try to start the iMac. My summer home iMac has some startup problem and I have to wait for the chime before I press the Option key, but it seems OK. It's a mystery...

Are you sure it's partitioned as GUID? That's the most likely problem...

I have my SuperDuper! backup on an external USB connected HD with an external power supply (formatted Mac OS Extended -- Journaled) and my last generation (early 2008) MBP boots just fine from it. (I'm using the firewire port for an older drive in a shell holding Time Machine).

Well, yes. Looking at the external USB disk with Disk Utility, it comes up with
"Partition Map Scheme: GUID Partition Table"
which is how I thought I formatted the partition. That means it's partitioned as GUID, no?

I note that SuperDuper *said* it was finishing up the clone by making it bootable. So ...

Now I do notice when I reboot with the OPTION key held down, the internal disk icon comes up immediately, and the light on the external disk keeps flashing. Maybe it's still trying to mount? I hold the OPTION key down for a full minute, but it never shows.

I guess I could just go out and get a FW enclosure for this disk, but I'd sure rather get this to work.

Does it appear as an option in the Startup Disk Preference Pane?

Yes, the disk does indeed appear as an option in the Startup Disk Preference pane, where the icon has the label "Mac OSX, 10.5.5 on backup".

("backup" is the name I gave the partition.)

So I guess that means that I could select it here, and boot from the external disk, but what I really want is a boot disk I could use if my system disk crashed and burned. If that happened, I'd never get to the Startup Disk Preference pane to select the external!

P.S. But, heh heh. When I select the external USB disk to be the startup disk in the Startup Disk preference pane (such that it says "You have selected Mac OSX, 10.5.5 on the volume 'backup' ") and I restart the machine, it still boots on the internal disk, which I can see by looking on the summary page on "About this Mac".

So even if I select the external USB disk as the startup disk, it just ignores it.

Indeed, when I then dismount and unplug the external USB disk, everything still is working, such that it really didn't boot from it.

Weird.

It is weird, but this sounds more like a hardware issue with the drive, not an issue with the copy.

Yes, it doesn't sound like the copy is a problem. I guess I'll take this external disk and try it in the same way on another machine. That might help resolve the question.

But thanks for the help!