Mac OS 9 disk drivers vs. OS X disk journalling

[gsteemso]

Back when I used to regularly dual-boot OS 9 and OS X, I periodically had to reinstall one or both systems due to disk corruption.

I tentatively concluded at the time that it might be because OS X used disk journalling, whereby every modification written to the disk is also logged for disaster recovery, and OS 9 did not. Thus, an I/O error under OS 9 – or even everyday disk activity – would be completely invisible to OS X, when the machine was next booted into it.

Did anyone else have a similar experience, and if so, what did you do about it?

 

[Byrd]

Different partitions with the first being OS 9 < 8GB, more for OS X and third partition for random files/MP3s etc - worked fine here.

 

[adespoton]

Different partitions with the first being OS 9 < 8GB, more for OS X and third partition for random files/MP3s etc - worked fine here.

Same here; the corruption problem generally seemed to be with the boot partition and interactions with Disk First Aid and Disk Utility. Worse corruption took place if Norton Disk Doctor was used.
As long as each OS gets its own partition, I've never had issues with HFS+ (or HFS) non-boot partitions that read/write from 10.5 and Mac OS 9 and earlier getting corrupted.

One thing to note: OS 8 and 9 run Disk First Aid at boot if they didn't shut down properly. You definitely don't want this to happen on a journaled partition with OS X installed. The only tool you should be running on an OS X partition is Disk Utility, and limit that to the version that matches the OS version. Disk Utility can also handle older HFS and HFS+ partitions, so best to use it instead of Disk First Aid or a third party tool.

 

[gsteemso]

I'd forgotten about the "automatically run Disk First Aid after a crash" thing. Now that you mention it, I strongly suspect that might have been the source of most of my problems. I _think_ I was running the OSes on their own partitions, so at least that part was probably OK. (It was a long time ago.) I'll have to do some poking around to see if I can disable the auto-Disk First Aid thing.

 

[mikes-macs]

What a great question. This explains a lot of issues over the years. The answers are great too. This needs to be added to my library of Macintosh Do's and Do Not s.