From owner-freebsd-fs  Wed Sep 20  2:16:58 2000
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From: Soren Schmidt <sos@freebsd.dk>
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Subject: Re: disable write caching with softupdates?
In-Reply-To: <200009200818.BAA27874@usr01.primenet.com> from Terry Lambert at "Sep 20, 2000 08:18:51 am"
To: tlambert@primenet.com (Terry Lambert)
Date: Wed, 20 Sep 2000 11:20:46 +0200 (CEST)
Cc: archie@whistle.com (Archie Cobbs), fs@FreeBSD.ORG,
	sos@FreeBSD.ORG
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It seems Terry Lambert wrote:
> > > > Isn't it safer (in the face of a power failure) to disable write
> > > > caching on a hard disk when softupdates is in use?
> > > 
> > > Yes.  You _must_ guarantee that the drive does not complete
> > > writes out of sequence that it reports having completed in
> > > sequence.  Hardware which lies is evil.
> > 
> > Hmm, the write caching on ATA drives (if they support it at all,
> > very few actually does), is guarantied to be able to write the
> > data to disk on power failure, or at least so they say, and I've
> > not been able to prove otherwise.
> 
> The ATA drives Whistle is using, which is what I'm assuming
> Archie is on about, do _not_ support this facility.  As far
> as I can tell, there wre some SCSI drives manufactured by
> IBM at one time which could do this, and some lab drives at
> Quantum (also SCSI).

Hmm, well, lets disable this then, there is no need to complicate
things :)

-Søren


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