Date: Sun, 18 Oct 1998 19:28:58 +0000 (GMT) From: Terry Lambert <tlambert@primenet.com> To: julian@whistle.com (Julian Elischer) Cc: guido@gvr.org, tlambert@primenet.com, dkelly@hiwaay.net, freebsd-fs@FreeBSD.ORG, freebsd-scsi@FreeBSD.ORG Subject: Re: filesystem safety and SCSI disk write caching Message-ID: <199810181928.MAA19832@usr06.primenet.com> In-Reply-To: <Pine.BSF.3.95.981017185905.11445A-100000@current1.whistle.com> from "Julian Elischer" at Oct 17, 98 06:59:41 pm
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> > I always thought a drive will always be able to flush its write cache > > to disk, even when power fails. > > no, > That's a myth. Actually, there are a number of drives which used to be manufactured, which did this. I don't think anyone is manufacturing them any more, but I know that at least one 7200 RPM IBM SCSI drive did this, and I have the spec sheets (somewhere) for a quantum that would so this, so long as the unwritten data was only a single track. Perhaps they realized that the mpst likely event after a power fluctuation was a bus reset, and figured "why bother?". Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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