From owner-freebsd-questions@FreeBSD.ORG Tue Oct 12 18:03:37 2004 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 5F64E16A4CF for ; Tue, 12 Oct 2004 18:03:37 +0000 (GMT) Received: from pi.codefab.com (pi.codefab.com [199.103.21.227]) by mx1.FreeBSD.org (Postfix) with ESMTP id 134B543D31 for ; Tue, 12 Oct 2004 18:03:37 +0000 (GMT) (envelope-from cswiger@mac.com) Received: from [192.168.1.3] (pool-68-160-246-51.ny325.east.verizon.net [68.160.246.51]) by pi.codefab.com (8.12.11/8.12.11) with ESMTP id i9CI3V9i030335 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 12 Oct 2004 14:03:33 -0400 (EDT) Message-ID: <416C1C59.1030207@mac.com> Date: Tue, 12 Oct 2004 14:03:05 -0400 From: Chuck Swiger Organization: The Courts of Chaos User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.3) Gecko/20040910 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Tom Oak References: <1097561796.27269.206262711@webmail.messagingengine.com> In-Reply-To: <1097561796.27269.206262711@webmail.messagingengine.com> X-Enigmail-Version: 0.86.1.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, hits=0.0 required=5.5 tests=none autolearn=no version=2.63 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on pi.codefab.com cc: freebsd-questions@freebsd.org Subject: Re: Avoid tar for Dell PowerVault 100T DAT 72 tape drive? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 12 Oct 2004 18:03:37 -0000 Tom Oak wrote: > The user's guide for the Dell PowerVault 100T DAT 72 tape drive recommends > against using tar (see quoted text below). Does anyone have any experience > with this product and can advise whether we should avoid tar? Thank you for > your help. The concern they have is valid, as tar defaults to using a tiny block size (512 or 2048 bytes, depending), which will cause the tape drive to start and stop rather than stream. Fortunately, you can either pipe tar into dd to change the blocksize, or else change the blocksize to something larger using the -b (--block-size for gnutar) option. For what it's worth, I've been using a blocksize of 126 (* 512, or 63K) with DLT drives for years now. Why 63K is (or was) faster than 32K or 64K or other values is not at all clear to me :-), so do your own testing to see. -- -Chuck