Sanity Check - large ISO support?

[dvpierce]

Power Macintosh G4, Adaptec 2930CU. ZuluSCSI 2040 external DB25.

Loaded up a DVD images to boot/install OS X 10.4. Boots halfway, computer powers off. CD ISOs worked fine, though. Much faster/better than burning CDs, so thank you all once again for this really great project and product.

Just wondering if it's supposed to work with a 2.8GB DVD ISO like that, or if I should interpret "CD-ROM emulation" more literally?

All my other bootable PPC OS X ISOs are CD-sized, except for the 10.5 ISO which is a smidge too big for my 8GB microSD cards, so while I know the next step would be to test other ISOs, I'm just asking here before I spend money. :-)

[aperezbios]

@dvpierce I believe the issue you're encountering is that OS X itself has a built-in assumption about the location of the CD-ROM drive being on the secondary IDE interface (which is the only place it's ever present on all G4 machines ever produced, for instance. It just doesn't support booting from SCSI CD-ROM at all. It took me quite some time to figure out what was going on the first few times it happened to me. You can tell this by examining the debug log output in real time over the USB console, where you can see the initial OS load (from OpenFirmware) works fine, but then once the Mach kernel is running, it never actually asks the ZuluSCSI for any more data, once it tries to mount the read-only root filesystem of the install CD.

That said, the ZuluSCSI firmware itself doesn't care at all what the size of the ISO is, and as far as I know of, there's no practical upper limit on ISO image size, beyond what will actually fit on any given SD card. Once OS X is booted and installed, it has no problem dealing with pseudo-CD/DVD images that are larger than 1-2GB, so the limitation is really confined to the install environment itself.