Re: 5-STABLE softupdates issue?

From: Scott Long <scottl_at_freebsd.org>
Date: Wed, 24 Nov 2004 07:01:48 -0700
Matthias Andree wrote:
> Greetings,
> 
> 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.
> 
> Unfortunately, I haven't copied the details, assuming they would be
> copied into the log, but they haven't.
> 
> Is this a situation the current 5-STABLE softupdates code (on a UFS1 FS
> that I kept from FreeBSD 4) is allowed to cause?
> 
> Is that a bug in the file system, say, write ordering goofed up?
> 
> Or is that a bug in the firmware of my disk drive (Western Digital
> Caviar AC420400D, a rebranded IBM DJNA drive)? I gather that ATA drives
> are supposed to flush their caches on software (command) and hardware
> resets (reset line active).
> 
> I did not power cycle.
> 

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.

Scott
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Received on Wed Nov 24 2004 - 15:33:47 UTC

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