From owner-freebsd-questions@FreeBSD.ORG Mon Jun 11 00:15:53 2012 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id EA5C81065672 for ; Mon, 11 Jun 2012 00:15:53 +0000 (UTC) (envelope-from roberthuff@rcn.com) Received: from smtp02.lnh.mail.rcn.net (smtp02.lnh.mail.rcn.net [207.172.157.102]) by mx1.freebsd.org (Postfix) with ESMTP id A86F78FC17 for ; Mon, 11 Jun 2012 00:15:53 +0000 (UTC) Received: from mr17.lnh.mail.rcn.net ([207.172.157.37]) by smtp02.lnh.mail.rcn.net with ESMTP; 10 Jun 2012 20:15:52 -0400 Received: from smtp04.lnh.mail.rcn.net (smtp04.lnh.mail.rcn.net [207.172.157.104]) by mr17.lnh.mail.rcn.net (MOS 4.3.4-GA) with ESMTP id BNM27356; Sun, 10 Jun 2012 20:15:52 -0400 Received: from 209-6-86-84.c3-0.smr-ubr2.sbo-smr.ma.cable.rcn.com (HELO jerusalem.litteratus.org.litteratus.org) ([209.6.86.84]) by smtp04.lnh.mail.rcn.net with ESMTP; 10 Jun 2012 20:15:52 -0400 From: Robert Huff MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <20437.14520.364554.528919@jerusalem.litteratus.org> Date: Sun, 10 Jun 2012 20:15:52 -0400 To: "Ronald F. Guilmette" In-Reply-To: <48774.1339367039@tristatelogic.com> References: <48774.1339367039@tristatelogic.com> X-Mailer: VM 7.17 under 21.5 (beta28) "fuki" XEmacs Lucid X-Junkmail-Whitelist: YES (by domain whitelist at mr17.lnh.mail.rcn.net) Cc: freebsd-questions@freebsd.org Subject: Re: Making a bootable backup (hard)disk... how? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 11 Jun 2012 00:15:54 -0000 Ronald F. Guilmette writes: > Warren? Just a couple more quick questions. You recommend: > > >> dump -C16 -b64 -0uanL -h0 -f - /usr | (cd /mnt && restore -ruf -) > > I'm real curious about you suggestions for the -C and -b values. > > I have what amounts to a personal workstation. Yea, OK, it is running > mail, web, and FTP servers also, but fundementailly, it is not that busy > most of the time. And it's got 4GB of main installed. On average, I > suspect that I ain't even using half of that. > > Given all that, why shouldn't I specify (e.g.): -C512 -b1024 ? > > Wouldn't that all make the dump go faster? There are many possible obstacles to faster dump speed; enumerating them is left as an exercise for the reader. As it happens, I have a set-up very similar to what you describe ... except with 8g of memory. A few years ago I did some testing with various cache sizes (as part of diagnosing other problems) and ended up with C=32. (I should probably run the tests again, given some hardware changes since.) That machine's level 0 runs tonight; I will try to remember to (retain and) post the results. Robert Huff