Subject: Re: disks write-back cache
To: Patrick Welche <>
From: Manuel Bouyer <>
List: tech-kern
Date: 04/28/2003 23:15:39
On Sun, Apr 27, 2003 at 03:05:42PM +0100, Patrick Welche wrote:
> This is fortuitous! Since the new ahc driver causes rubbish to be written
> to my disks, at least this is something to try: tagged queueing is enabled,
> and so is write-back cache... Will try switching off write-back cache
> on Tuesday...

Well, I've done some tests on my sparc64, and I've not been able to reproduce
this problem ...

However, I've seen once what I believe was a (SCSI) disk with a bad cache.
Once in a while I would get corruption of a read-only filesystem (mounted
read/write, but almost never written to). The affected blocks were always
the same. The disk didn't report any error, and the others disks on the same
bus didn't have this problem. I remplaced the disk with another one, of the
exact same model, and I've not seen this problem since.

Manuel Bouyer <>
     NetBSD: 24 ans d'experience feront toujours la difference