From owner-freebsd-stable@FreeBSD.ORG Wed Nov 15 11:45:15 2006 Return-Path: X-Original-To: freebsd-stable@FreeBSD.ORG Delivered-To: freebsd-stable@FreeBSD.ORG Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id F315D16A40F for ; Wed, 15 Nov 2006 11:45:14 +0000 (UTC) (envelope-from olli@lurza.secnetix.de) Received: from lurza.secnetix.de (lurza.secnetix.de [83.120.8.8]) by mx1.FreeBSD.org (Postfix) with ESMTP id 4FD0D43D67 for ; Wed, 15 Nov 2006 11:45:13 +0000 (GMT) (envelope-from olli@lurza.secnetix.de) Received: from lurza.secnetix.de (tytmli@localhost [127.0.0.1]) by lurza.secnetix.de (8.13.4/8.13.4) with ESMTP id kAFBj7qw091657; Wed, 15 Nov 2006 12:45:12 +0100 (CET) (envelope-from oliver.fromme@secnetix.de) Received: (from olli@localhost) by lurza.secnetix.de (8.13.4/8.13.1/Submit) id kAFBj7D0091656; Wed, 15 Nov 2006 12:45:07 +0100 (CET) (envelope-from olli) Date: Wed, 15 Nov 2006 12:45:07 +0100 (CET) Message-Id: <200611151145.kAFBj7D0091656@lurza.secnetix.de> From: Oliver Fromme To: freebsd-stable@FreeBSD.ORG, uspoerlein@gmail.com In-Reply-To: <7ad7ddd90611150257w4e2a787dt3d644de2423bd4c9@mail.gmail.com> X-Newsgroups: list.freebsd-stable User-Agent: tin/1.8.2-20060425 ("Shillay") (UNIX) (FreeBSD/4.11-STABLE (i386)) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-2.1.2 (lurza.secnetix.de [127.0.0.1]); Wed, 15 Nov 2006 12:45:13 +0100 (CET) Cc: Subject: Re: dump(8): how many bytes written to tape? X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: freebsd-stable@FreeBSD.ORG, uspoerlein@gmail.com List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 15 Nov 2006 11:45:15 -0000 Ulrich Spoerlein wrote: > I'm trying to figure out how much bytes were written to a tape by > dump(8). I'm using a blocksize of 64kB to maximize throughput to the > tape drive. Initially, I thought I could just add up the number of > "tape blocks" written by dump and multiply by 64kB. But it looks like > dump is still reporting those values as 1kB blocks. > [...] > So, how exactly is the '-b64' parameter to dump(8) affecting the block > size on tape? The -b option does _not_ change the blocksize of dump, which is hardcoded at 1024 bytes and cannot be changed. That means that the reported number of blocks is also always measured in units of 1024 bytes, no matter what your -b option says. Unfortunately the manual page is somewhat misleading. :-( Instead, the -b option changes the number of blocks per record, i.e. how many blocks are written at once per write operation. The default is 10 for standard tapes and 32 for high-density tapes (>= 6250 bpi). Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing Dienstleistungen mit Schwerpunkt FreeBSD: http://www.secnetix.de/bsd Any opinions expressed in this message may be personal to the author and may not necessarily reflect the opinions of secnetix in any way. "It combines all the worst aspects of C and Lisp: a billion different sublanguages in one monolithic executable. It combines the power of C with the readability of PostScript." -- Jamie Zawinski, when asked: "What's wrong with perl?"