How do I get my Mirror Drive Door G4 to start up in 9.2.2? Retail disk doesn't work.

Question

So my boss came in with a Mirror Drive Door G4 running 10.3.x and told me to get OS9 running on it. "Piece of cake," I told him.
Just as the curmudgeon at the used PC store assured me, my retail copy of OS9 will NOT install onto it. One MUST use the restore disks specific to this machine, he said. Seemed counter-intuitive, that a retail copy of OS9 somebody had paid for would not install 9 onto a mac that can run 9. But he was right. So I bought CDR copies of the restore disks that came with the MDD. Whether these pertain to the exact MDD I'm using is another question.
After much headache, I was able to get run the OS9 system restore package cuncluded by a window that reported success. The startup disk preference window in OSX could see the 9.2.2 system folder. I selected it and restarted. It tried, but then stopped, made another unreasonably loud JONG noise and presented me with a flashing "no OS folder" icon. I was only able to start back up using a 10.3 install disk to select the 10.3 system folder on the HD.
This machine is able to start up in OS9 if I install an old HD from my ancient snow iMac into it. What's that about? It can start up using that non-MDD-specific system folder but not the one specific to this machine?
The drive I'm having trouble starting up from was erased with OS9 drivers installed before 10.3 was installed, followed by 9.2.2 from the restore disks.
What am I doing wrong?
Thanks folks.

Answer 1

Yes, there is.
OS 9 can not boot when installed on a volume larger than 200GB.
The good news is that this is a volume size limitation, not a drive size limitation. This means that you can partition a drive larger than 200GB such that the volume used for OS 9 booting is not larger than 200GB; to allow for formatting wiggle room, using a max volume size of about 190GB is safer.
When reforatting the drive, remember to make sure tha OS 9 drivers are installed.