From owner-freebsd-questions Thu Oct 4 17:47:57 2001 Delivered-To: freebsd-questions@freebsd.org Received: from guru.mired.org (okc-65-31-203-60.mmcable.com [65.31.203.60]) by hub.freebsd.org (Postfix) with SMTP id 594BA37B401 for ; Thu, 4 Oct 2001 17:47:52 -0700 (PDT) Received: (qmail 71461 invoked by uid 100); 4 Oct 2001 20:47:45 -0000 From: Mike Meyer MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <15292.51953.728016.474117@guru.mired.org> Date: Thu, 4 Oct 2001 15:47:45 -0500 To: Zhihui Zhang Cc: Magdalinin Kirill , questions@FreeBSD.ORG Subject: Re: turning off write cache on SCSI drive In-Reply-To: References: <15292.48443.672916.539479@guru.mired.org> X-Mailer: VM 6.90 under 21.1 (patch 14) "Cuyahoga Valley" XEmacs Lucid X-face: "5Mnwy%?j>IIV\)A=):rjWL~NB2aH[}Yq8Z=u~vJ`"(,&SiLvbbz2W`;h9L,Yg`+vb1>RG% *h+%X^n0EZd>TM8_IB;a8F?(Fb"lw'IgCoyM.[Lg#r\ Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Zhihui Zhang types: > On Thu, 4 Oct 2001, Mike Meyer wrote: > > > Magdalinin Kirill types: > > > Hello, > > > some mail posts on softupdates says that turning off write cache is > > > prerequisite for it. > > They're generally talking about IDE drives. SCSI drives have tagged > > queuing, which means you're perfectly safe doing this. > Why tagged queuing make it safe to turn WCE on? The problem that WCE presents is that a write to the drive returns, but the data isn't really on the drive. Tagged queuing allows the drive to tell the software when the data is really on the drive. http://www.mired.org/home/mwm/ Q: How do you make the gods laugh? A: Tell them your plans. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message