Mac OS 9 booting: HARD DISK SIZE LIMIT ?

Question

Mac OS 9 booting: HARD DISK SIZE LIMIT ?

I have Mac OS 9.2.2 and Mac OS X 10.4.2 installed on the same hard disks (single partition).

I can boot from Mac OS X from all disks, but I can only only boot Mac OS 9.2.2 from small ones. In particular, I cannot boot Mac OS 9.2.2 from disks with 300, 400 or 500 GB. I have used Apple Migration Assistant to move data from old-smaller to new-larger disks only to discover this booting problem.

Any Apple official information to cover this issue?

Thanks.

Posted on Oct 25, 2005 6:22 AM

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Answer 1

Oct 25, 2005 7:48 AM in response to Gabriel Dorado

Hi, Gabriel -

OS 9 has a usable/addressable volume limit of about 190GB. This is a volume limit, not a drive size limit - partitioning a larger drive will allow all partitions that size or smaller to be used in OS 9.

This is in addition to the hardware limits of the internal IDE bus, which is not OS-based. The built-in bus on a G4/500 (AGP) is an ATA/66 bus - its limit is 128GB drive size. Adding a 48-bit LBA compliant ATA/100 or ATA/133 PCI card will allow larger drives to be used internally.

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Answer 2

Oct 25, 2005 9:44 AM in response to Don Archibald

Don,

Thanks. That explains it.

Do you know of any Apple document or web page indicating such figures?

Thanks.

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Answer 3

Oct 25, 2005 1:15 PM in response to Gabriel Dorado

Hi, Gabriel -

This Apple Kbase article briefly addresses those numbers -
http://docs.info.apple.com/article.html?artnum=86178

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Answer 4

Oct 25, 2005 1:33 PM in response to Don Archibald

Don,

Thanks.

Well, there it says:

---
Not all Macintosh products can take advantage of the full capacity of large (128 GB or greater) hard drives that use 48-bit LBA when they are connected via an ATA controller. Other controllers (SCSI or FireWire) are not affected.
---

Yet, in my case the disks were all external FireWire and generated the problem (cannot boot Mac OS 9.2.2 from them). So, it seems that FireWire disks are also affected afrter all and not only the ATA ones.

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Answer 5

Oct 25, 2005 2:40 PM in response to Gabriel Dorado

Hi, Gabriel -

The ATA issue affects primarily the drive size - a hardware limit applicable to the ATA controller in use. This limit (the 128GB limit) does not apply to firewire.

The OS 9 volume limit issue is OS-based, not hardware-based, and does apply to firewire.

From that article -
If you plan to start the partition up from Mac OS 9.2.2, the partition sizes may be a maximum of 200 GB.

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Answer 6

Oct 25, 2005 2:48 PM in response to Don Archibald

Don,

Thanks!

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Answer 7

Oct 25, 2005 3:46 PM in response to Gabriel Dorado

Hi, Gabriel -

You're quite welcome.

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