5-STABLE softupdates issue?

Dan Nelson dnelson at allantgroup.com
Wed Nov 24 09:18:57 PST 2004


In the last episode (Nov 24), Scott Long said:
> Matthias Andree wrote:
> > out of fun and to investigate claims about alleged bgfsck resource
> > hogging (which I could not reproduce) posted to
> > news:de.comp.os.unix.bsd, I pressed the reset button on a live
> > FreeBSD 5-STABLE system.
> >
> > Upon reboot, fsck -p complained about an unexpected softupdates
> > inconsistency on the / file system and put me into single user
> > mode, the manual fsck / then asked me to agree to increasing a link
> > count from 21 to 22 (and later to fix the summary, which I consider
> > a non-issue). A subsequent fsck -p / ended with no abnormality
> > detected.
> 
> No, this in theory should not happen.  YOu could have caught it right
> at the instance that it was sending a transaction out to disk, or you
> could have caught an edge case that isn't understood yet. 
> Unfortunately, ATA drives also cannot be trusted to flush their
> caches when one would expect, so this leaves open a lot of possible
> causes for your problem.

If you just want to test stability in the face of system crashes (and
not power failure), you can drop to DDB and run "reboot" to simulate a
panic (or run reboot -qn as root).  That way your drive doesn't lose
power.

That said, I get unexpected softupdates inconsistencies pretty
regularly on kernel panics.  I just let the system run until I can
reboot and run a fsck -p.

-- 
	Dan Nelson
	dnelson at allantgroup.com


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