From owner-freebsd-scsi@FreeBSD.ORG Sun Jun 1 17:00:24 2003 Return-Path: Delivered-To: freebsd-scsi@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 3933537B401 for ; Sun, 1 Jun 2003 17:00:24 -0700 (PDT) Received: from beppo.feral.com (beppo.feral.com [192.67.166.79]) by mx1.FreeBSD.org (Postfix) with ESMTP id 767AD43FAF for ; Sun, 1 Jun 2003 17:00:23 -0700 (PDT) (envelope-from mjacob@feral.com) Received: from mailhost.feral.com (mjacob@mailhost.feral.com [192.67.166.1]) by beppo.feral.com (8.12.9/8.12.9) with ESMTP id h5200Iqw097301; Sun, 1 Jun 2003 17:00:22 -0700 (PDT) (envelope-from mjacob@feral.com) Date: Sun, 1 Jun 2003 17:00:18 -0700 (PDT) From: Matthew Jacob X-X-Sender: mjacob@beppo To: Kern Sibbald In-Reply-To: <1054503893.1578.1723.camel@rufus> Message-ID: <20030601165751.H97138@beppo> References: <1054490081.1582.1685.camel@rufus> <2846020000.1054498114@aslan.scsiguy.com> <1054503893.1578.1723.camel@rufus> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII cc: freebsd-scsi@freebsd.org Subject: Re: SCSI tape data loss X-BeenThere: freebsd-scsi@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list Reply-To: mjacob@feral.com List-Id: SCSI subsystem List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 02 Jun 2003 00:00:24 -0000 Of course linux has async && buffered. Linux has to copy the data from user space to kernel buffers and *then* write them. This leads to an obvious desire to overlap such writes. The same feature was available in Solaris 2.5 as well. 'Buffering' as we talk about here typically means the device buffers themselves. You don't want to turn this off. You don't want to turn this off. You don't want to turn this off. The only device that I know of that really *has* to have this off is the old M4 1/2" reel drive because it would discard buffered data when it saw the early warning marker. I have a longer answer to the previous mail about to go out. -matt