The problem is more likely that only the very last PPC models to come out supported booting via USB at all, and then it was only if you went quite a ways out of your way.
I'm highly skeptical that it has anything to do with the journaling. The filesystem itself is the same, all journaling is, is basically the filesystem writes down what it plans to do, then does it. It's a purely optional function, and in fact you can turn it on/off in OS X on a whim with Disk Utility. So if for some reason you were trying to use a journaled filesystem on an older version of Mac OS X that didn't support that, it should still be able to access the drive. You just wouldn't have the added fault tolerance of the journaling. All the journaling really is, after all, is a special log file on the drive where the commands the filesystem is going to carry out are written down. That way if the process is interrupted, it knows what it still needs to do. When you look at what it actually is, it's really far less impressive than most make it out to be in their minds.
So the more likely scenario here seems to be that yours is not a model that can do booting off of USB.
I've had a bad run of luck this year, dropping my powerbook g4, and mucking up my harddrives. I basically want to back up my entire OS as a .dmg to an external drive, and when I need to, restore from it. Since it's an old Powerbook, it's running with the PPC chip, and there is no support for booting via USB. I know the work-around (go into Open Firmware, find the USB device, find the boot file in the connected media, command it to boot from that file location), but in order to do this, I need an external HD that I can format in Mac OSX Extended.
When I use Disk Utility, it automatically formats the device (in this case, a WD Elements 1 Tb drive) as OSX Extended (journaled). The partition it makes is not journaled, but when I look at the main device, it's always journaled.
The problem here, as I understand it, is that the Open Firmware can't see the file tree on the MOSXE(J) format. That prevents finding the boot file, which prevents booting from that media via USB.
I've done it before, with someone else's external, during a previous "rescue", but my WD external, or perhaps Disk Utility doesn't want to cooperate.
Does anyone know why, and have a workaround for it?

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