Jaguar Checks Disks?

[Ian Sidle]

> I've heard rumors (if you want to call it that) that Jaguar (and maybe
> other versions of OS X) run the fsck command (to check/repair disks) in
> the background at startup - is this true?

Short answer - Yes and no.

Long answer..
No. It is not possible for fsck to run in the background on any 
*running* file system. I guess they could have it run on a non-system 
disk while booting, but thats kind of excessive and likely you would 
wait for the disk to run disk repair. Now with the new journalized 
filesystem mode for HFS+, it might be possible to run "fsck" on the 
filesystem while its startup. While "fsck" would mean "disk repair 
stuff" on the drive, not fsck itself. For the FS being journalized, it 
gets mounted and the journal file is examined and the file system is 
updated for the modifications in it.. so technically, its mounted and 
"running" but this takes a few seconds (if that) which would then be 
complete before the os has started up completely.

One interesting note was that I have an external firewire-ide case I 
got some time ago. I obtained a 2nd hand hd from a windows/pc machine 
and put it in such box. I plugged it into my ibook (while running) and 
the disk activity light popped on on the drive but the drive didn't 
mount (didn't show up on the desktop). Upon running "top -u" it showed 
that fsck_msdos was running at 100%. I guess the fs was damaged and why 
it was taken out.. So After waiting an hour and it still not coming up, 
I manually killed fsck and ran disk utility and reformatted the drive 
(which I was going to do anyway). So in that case, fsck was running in 
the background but not on the system disk.. I'm not sure if this would 
be done on a HFS drive or not.. and this probably could be a problem 
for some who is not as knowledgeable as me.. although eventually I 
think the check would have finished anyway.

Hope that answers your question.

thanks,
Ian Sidle