From owner-freebsd-fs Fri Jan 31 12:40:34 2003 Delivered-To: freebsd-fs@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id E3E4B37B401; Fri, 31 Jan 2003 12:40:32 -0800 (PST) Received: from sccrmhc03.attbi.com (sccrmhc03.attbi.com [204.127.202.63]) by mx1.FreeBSD.org (Postfix) with ESMTP id 44A3243FA7; Fri, 31 Jan 2003 12:40:32 -0800 (PST) (envelope-from julian@elischer.org) Received: from interjet.elischer.org (12-232-168-4.client.attbi.com[12.232.168.4]) by sccrmhc03.attbi.com (sccrmhc03) with ESMTP id <2003013120403000300jupd0e>; Fri, 31 Jan 2003 20:40:30 +0000 Received: from localhost (localhost.elischer.org [127.0.0.1]) by InterJet.elischer.org (8.9.1a/8.9.1) with ESMTP id MAA46556; Fri, 31 Jan 2003 12:40:29 -0800 (PST) Date: Fri, 31 Jan 2003 12:40:28 -0800 (PST) From: Julian Elischer To: phk@freebsd.org Cc: Steve Byan , freebsd-fs@freebsd.org, tech-kern@netbsd.org Subject: Re: DEV_B_SIZE In-Reply-To: <31671.1044043107@critter.freebsd.dk> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-fs@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org On Fri, 31 Jan 2003 phk@freebsd.org wrote: > In message , Ju > lian Elischer writes: > > > > > >One thign I thought of is that it is not uncommon to 'dd' an entire > >filesystem from one partition to another. > >If we create a filesystem that is 'aligned' and we copy it to be > >'unalligned', we'd have a sudden performance drop for no immediatly > >obvious reason. What was one write, would become a 2-sector read, > >modify and 2-sector write. Especially when copying from one failing > >drive to another with slightly different characteristics. > > If you run dd without bs=ALOT you deserve bad throughput. I'm talking about the performance of the filesystem after it's been moved. > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > phk@FreeBSD.ORG | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by incompetence. > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message