Subject: Re: Playing with dkwedge
To: Bill Studenmund <>
From: Manuel Bouyer <>
List: tech-kern
Date: 08/23/2005 14:51:54
On Mon, Aug 22, 2005 at 04:51:49PM -0700, Bill Studenmund wrote:
> > I'd still like to see a fsck -n run in the daily script on journaled file
> > system. Usefull to detect corruption (the daily fsck -n has already pointed
> > me hardware problems before they became too bad).
> I think a better solution to this is to run a background scrubber script. 
> All you need to do is read data, you don't need to calculate bitmaps & 
> such. And it'd also be good to read raw data areas, not just metadata 
> areas.
> Such a tool would help with the reliability of RAID 5 systems and keep a 
> disk failure from turning into a fatal double error (finding a bad block 
> when one disk is down).

This would be good to have too, but it doesn't remplace a periodic consistency
check of the filesystem. In one case where this helped me, it was the
drive which was returning bogus data sometimes (I suspect its internal
cache memory was bad, or something like that). The system would end up 
panicing in the fileystem code, but the daily fsck showed the problem before
the panic occured.

Manuel Bouyer <>
     NetBSD: 26 ans d'experience feront toujours la difference