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Date:      Wed, 14 Oct 1998 09:48:52 -0400 (EDT)
From:      Bill Vermillion <bill@bilver.magicnet.net>
To:        freebsd-fs@FreeBSD.ORG
Subject:   Re: filesystem safety and SCSI disk write caching
Message-ID:  <199810141348.JAA10202@bilver.magicnet.net>
In-Reply-To: <199810140518.XAA15040@pluto.plutotech.com> from "Justin T. Gibbs" at "Oct 13, 98 11:11:41 pm"

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Justin T. Gibbs recently said:

> >> >It doesn't, since "# of anomalies == 0" with write caching
> >> >disabled.
> >>
> >> This doesn't follow. If the cache is disabled, it doesn't
> >> matter if the drive loses power due to hitting the reset
> >> button. We already know that losing power on a drive that
> >> cached data will not work.

> >We do?

> Of course we do. Why do you think my position on this subject has
> always been, "Write caching is fine so long as you use a UPS"?

There was at least one model of IBM's high-end SCSI drives which
when power was lost, would use the inertia from the spinning
platters to generate current from the motor, in order to flush the
on-board drive cache.

Anyone recall that model number?


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