From owner-freebsd-scsi Tue Oct 13 22:23:31 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id WAA11353 for freebsd-scsi-outgoing; Tue, 13 Oct 1998 22:23:31 -0700 (PDT) (envelope-from owner-freebsd-scsi@FreeBSD.ORG) Received: from pluto.plutotech.com (mail.plutotech.com [206.168.67.137]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id WAA11344; Tue, 13 Oct 1998 22:23:29 -0700 (PDT) (envelope-from gibbs@plutotech.com) Received: from narnia.plutotech.com (narnia.plutotech.com [206.168.67.130]) by pluto.plutotech.com (8.8.7/8.8.5) with ESMTP id XAA15206; Tue, 13 Oct 1998 23:23:12 -0600 (MDT) Message-Id: <199810140523.XAA15206@pluto.plutotech.com> X-Mailer: exmh version 2.0.2 2/24/98 To: Don Lewis cc: "Justin T. Gibbs" , Terry Lambert , freebsd-fs@FreeBSD.ORG, freebsd-scsi@FreeBSD.ORG Subject: Re: filesystem safety and SCSI disk write caching In-reply-to: Your message of "Tue, 13 Oct 1998 21:39:50 PDT." <199810140439.VAA17463@salsa.gv.tsc.tdk.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Tue, 13 Oct 1998 23:16:27 -0600 From: "Justin T. Gibbs" Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org >} 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. > >I didn't hear the sound of any mechanical things spinning down. The >machine just started going through its boot sequence. The drive will reinitialize to the 'power on state' if the power fluctuates into a zone that might invalidate it's run-time state. It doesn't take a very long spike for the drive's power-glitch sensor to go off. In this case, dropping cached contents on the floor is much safer than attempting to continue from an unknown state. -- Justin To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message