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Old 07-21-2009, 01:28 AM
Staxman Staxman is offline
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Join Date: Apr 2004
Location: Seattle, WA: the belly of the beast!
Posts: 15
Partition table and bootability

I have a G4 iMac running OS X 10.4.11. For ~2 years I've been cloning my internal HD to an Other World Computing Mercury On-the-Go drive:

http://eshop.macsales.com/shop/firewire/on-the-go

A few months ago I picked up a Verbatim external drive from one of the online vendors (Buy.com, Newegg.com, I forget who). I started cloning my drive to the Verbatim drive also. Both external drives are enough bigger than my internal HD that I have multiple partitions on each, so I have quite a few clones available at any given time. I partitioned each drive at the time I got it.

Long story short, some recent events (and a discussion on another Mac forum) led me to take a closer look at the partitioning schemes on the drives. I found that the OWC drive was partitioned with Apple Partition Map (not surprising, coming from OWC), and the Verbatim drive was partitioned with Master Boot Record.

Whenever I've made a clone, the Mac has seemed to reboot successfully from the external drive, and according to System Preferences, the external drive has been set as the boot drive. Once the computer was up and running, I've gone into System Preferences, set the boot drive to my internal drive, and rebooted.

According to the discussion on the other forum, my Mac shouldn't have been able to boot from the Verbatim drive. Just as a test, I plugged in the Verbatim drive and depressed Option as the system was coming up. I was offered only the internal drive as a possible boot drive. This leaves me wondering what's really been going on when I've thought I was booting from the Verbatim drive. If I can't boot from the Verbatim drive, shouldn't the system be telling me so?

This also seems odd to me because about 3 years ago I had an experience (which I posted about here at the time) with an external drive whose chipset didn't support booting. In that case, the computer was clearly not booting from the external drive. I wound up using that for offline storage and got the OWC drive.

I realize that I could boot the system from the OS X install DVD and restore from the Verbatim drive, but I think that defeats the purpose of using SuperDuper. If I have to repartition the Verbatim drive with Apple Partition Map, so be it.

Thanks.
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