From owner-freebsd-stable Tue Mar 2 18:39:58 1999 Delivered-To: freebsd-stable@freebsd.org Received: from mail.HiWAAY.net (fly.HiWAAY.net [208.147.154.56]) by hub.freebsd.org (Postfix) with ESMTP id 2088714E23 for ; Tue, 2 Mar 1999 18:38:59 -0800 (PST) (envelope-from dkelly@nospam.hiwaay.net) Received: from nospam.hiwaay.net (tnt8-216-180-15-176.dialup.HiWAAY.net [216.180.15.176]) by mail.HiWAAY.net (8.9.1a/8.9.0) with ESMTP id UAA23291; Tue, 2 Mar 1999 20:38:41 -0600 (CST) Received: from nospam.hiwaay.net (localhost [127.0.0.1]) by nospam.hiwaay.net (8.9.2/8.9.2) with ESMTP id UAA10662; Tue, 2 Mar 1999 20:38:38 -0600 (CST) (envelope-from dkelly@nospam.hiwaay.net) Message-Id: <199903030238.UAA10662@nospam.hiwaay.net> X-Mailer: exmh version 2.0.2 2/24/98 To: Tom Cc: freebsd-stable@FreeBSD.ORG From: David Kelly Subject: Re: rc5des slows tape thruput In-reply-to: Message from Tom of "Tue, 02 Mar 1999 18:12:43 PST." Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Tue, 02 Mar 1999 20:38:38 -0600 Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Tom writes: > On Tue, 2 Mar 1999, David Kelly wrote: > > What if you write 1MB ahead into the tape drive, then hit the end of > > tape? How would one attempt to recover from that? It seems the Un*x > > architects intend to be able to recover from that situation altho in > > practice its unreliable. It seems only one block at a time is given to > > the drive, and the drive doesn't ask for more until the first is safely > > on tape. > > Well, that is assuming the buffer is used for writing. I suspect tape drive RAM is mostly used for buffering during compression. Haven't been trying compression and even went to extended effort to disable compression on all my DDS drives. But am guessing comprssion might invoke buffering. -- David Kelly N4HHE, dkelly@nospam.hiwaay.net ===================================================================== The human mind ordinarily operates at only ten percent of its capacity -- the rest is overhead for the operating system. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message