Date: Thu, 05 Jul 2001 14:53:24 -0700 From: Peter Wemm <peter@wemm.org> To: Poul-Henning Kamp <phk@critter.freebsd.dk> Cc: Ben Smithurst <ben@FreeBSD.org>, cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/etc diskcheckd.conf Message-ID: <20010705215324.448BA3809@overcee.netplex.com.au> In-Reply-To: <6446.994361127@critter>
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Poul-Henning Kamp wrote:
> In message <20010705151553.E97328@strontium.shef.vinosystems.com>, Ben Smithu
rs
> t writes:
>
> >I'm tempted to think the default diskcheckd.conf shouldn't check
> >anything, checking everything by default seems to be causing trouble.
> >
> >Poul-Henning, what's your view?
>
> How about checking all disks which:
> are larger than 1G and do not contain "cd" in their name ?
> as default ?
For what its worth, I have yet to see a modern drive that does do scrubbing
of marginal data. Ie: a soft error (ecc correctable) does not cause
a writeback that I have ever seen.
I have a really revolting program that I wrote years ago that did bad block
scanning and scrubbing in userland. I had an opportunity to use it a few
months ago on a disk that had got too hot and was getting lots of retries
and ECC corrections. (ie: it was really really slow at reading). I used
the 'rewrite' option in my hack program, which reads into a large buffer
and rewrites a few megabytes behind. The problems went away and it resumed
full speed. (This was a quantum 30G ATA disk). I wrote the program for
scsi disks years ago, and I certainly recall similar behavior there too -
which is why I even added the rewrite option to the scanner.
I am not sure that the basic assumption behind diskcheckd is valid.. Is
there any way to verify for sure that marginal sector scrubbing really
happens on at least some drives?
Cheers,
-Peter
--
Peter Wemm - peter@FreeBSD.org; peter@yahoo-inc.com; peter@netplex.com.au
"All of this is for nothing if we don't go to the stars" - JMS/B5
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