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Level 1

4 points

External HD Boot fails with Snow Leopard

When I try to boot from an external HD with 10.6 installed I get a kernel panic "unable to find a driver for this platform". My internal drive has 10.7 installed. Any suggestions as to how to resolve the issue?

Here's a bit of background. I have some files on my computer that are produced by applications no longer supported on the Mac. They worked fine under Rosetta with 10.6 but when I upgraded to 10.7 and Rosetta was dropped, so did my ability to access the files. I'm really keen to be able to at least open the files and see if I can export them to useful format, or even print them.

Today I purchased an external 1TB HD in the hope that this would solve my problem. I intended to boot up using Snow Leaopard. I installed it using the DVD purchased as part of the Mac Boxed Set a while back. There are two partitions on the HD, a 50GB section with 10.6 on it and a 950GB which is blank.

When the installation was complete the Mac automatically rebooted. Unfortunately it panicked midway through the restart. I've tried re-initialising the drive and checking the firmware. Everything seems ok there. I'm not sure what to do next.

Peter

iMac, Mac OS X (10.7.3)

Posted on Mar 17, 2012 4:42 AM

23 replies

peterpumpkin Author

Level 1

4 points

Mar 18, 2012 12:56 AM in response to X423424X

Ok did that and was able to boot from the external using 10.7.3.

X423424X

Level 6

14,265 points

Mar 18, 2012 1:31 AM in response to peterpumpkin

Ok, well that answers that question. Looks like the box can boot lion so I would assume it could boot snow leopard (...he thinks to himself, "is that a valid assumption?"...).

So to reiterate (please confirm), you have the retail version of Snow Leopard. You run part 1 of that installer on to that external, part 1 completes, and tries to reboot from the external to go through the Setup Assistant and that is when you get the "unable to find a driver for this platform" error. Is this all true?

If this is what is happening, another experiment. After part 2 of the install fails reboot with the option key down and see if the external is one of the boot choices. If it is choose it and see if the Setup Assistant starts now. I'm just curious what happens.

I'm also wondering if somehow you have a bad copy of the installer.

peterpumpkin Author

Level 1

4 points

Mar 18, 2012 2:59 AM in response to X423424X

I found an old 60GB external drive from a laptop. I erased and then reformatted it using the Snow Leopard disks. It installed ok and got through the boot up to the Setup Assistant. It seems to run fine. I'm now following the same procedure with the 1TB drive. Perhaps it will boot properly too. I thought I had used the installation disk's copy of Disk Utility to format the 1TB drive. However, when I erased the disk first using the install disk's Disk Utility, the capacity of the drive was marginally smaller, indication some variation in the format. I'm hoping this will solve the issue.

Mar 18, 2012 3:44 AM in response to peterpumpkin

It's normal for the usable capacity of a formatted drive to be slightly less than the nominal capacity. The space is taken up by the formatting information put there by DU.

peterpumpkin Author

Level 1

4 points

Mar 18, 2012 5:51 AM in response to noondaywitch

What I meant was that the formatted capacity was marginally smaller when formatted with Disk Utility for Snow Leopard compared with the formatted capacity when using Disk Utility for Lion.

peterpumpkin Author

Level 1

4 points

Mar 18, 2012 5:57 AM in response to peterpumpkin

Well a new issue has arisen. The system doesn't panic on startup anymore, however it won't boot into 10.6 from the 1TB external. Instead it bypasses the external and boots with 10.7.3 from the internal hard drive. At one stage I think I momentarily saw the Apple logo change to the universal denial symbol, a circle with a slash through it. It was so quick, it was like a subliminal image in a movie.

In any case I can now log in using 10.6 on the smaller hard drive. That's fine. I'll contact LaCie support and see what they can recommend. If the problem is fixed I'll post a follow up message here.

X423424X

Level 6

14,265 points

Mar 18, 2012 12:36 PM in response to peterpumpkin

What I meant was that the formatted capacity was marginally smaller when formatted with Disk Utility for Snow Leopard compared with the formatted capacity when using Disk Utility for Lion.

Recovery partition maybe.

Well a new issue has arisen. The system doesn't panic on startup anymore, however it won't boot into 10.6 from the 1TB external. Instead it bypasses the external and boots with 10.7.3 from the internal hard drive. At one stage I think I momentarily saw the Apple logo change to the universal denial symbol, a circle with a slash through it. It was so quick, it was like a subliminal image in a movie.

What is the default boot drive? Check the Startup Disk system preferences.

peterpumpkin Author

Level 1

4 points

Mar 18, 2012 10:19 PM in response to peterpumpkin

Thanks to everyone who offered ideas and support. I'm able to access my files now rather than sitting here frustrated and wondering what went wrong. Cheers! Hope I can help you guys in some way some time.

External HD Boot fails with Snow Leopard