From owner-freebsd-current@FreeBSD.ORG Wed Jan 6 11:36:34 2010 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 829301065679; Wed, 6 Jan 2010 11:36:34 +0000 (UTC) (envelope-from des@des.no) Received: from smtp.des.no (smtp.des.no [194.63.250.102]) by mx1.freebsd.org (Postfix) with ESMTP id 40AB68FC1B; Wed, 6 Jan 2010 11:36:34 +0000 (UTC) Received: from ds4.des.no (des.no [84.49.246.2]) by smtp.des.no (Postfix) with ESMTP id 5E11F1FFC22; Wed, 6 Jan 2010 11:36:33 +0000 (UTC) Received: by ds4.des.no (Postfix, from userid 1001) id C331E844C2; Wed, 6 Jan 2010 12:36:32 +0100 (CET) From: =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= To: "Svein Skogen \(Listmail Account\)" References: <65036.1262386032@critter.freebsd.dk> <201001020101.16450.pieter@degoeje.nl> <86637fjypj.fsf@ds4.des.no> <4B446E52.4030508@stillbilde.net> Date: Wed, 06 Jan 2010 12:36:32 +0100 In-Reply-To: <4B446E52.4030508@stillbilde.net> (Svein Skogen's message of "Wed, 06 Jan 2010 12:04:50 +0100") Message-ID: <86wrzvihxb.fsf@ds4.des.no> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.0.95 (berkeley-unix) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Cc: Alexander Motin , Miroslav Lachman <000.fbsd@quip.cz>, Thomas Backman , Poul-Henning Kamp , freebsd-current@freebsd.org, freebsd-arch@freebsd.org, Pieter de Goeje Subject: Re: File system blocks alignment X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 06 Jan 2010 11:36:34 -0000 "Svein Skogen" writes: > Dag-Erling Sm=C3=B8rgrav writes: > > Or just default to 4 kB or even 8 kB, which has zero performance impact > > (either way) for disks with 512 B sectors. > I'd like it to be tunable. It already *is* tunable, and always has been - it's just a matter of selecting the correct offsets and sizes when you partition the disk / array, and using the correct newfs parameters. The problem is the default alignment used by fdisk, gpart etc. Fdisk aligns slices on cylinder boundaries, even though cylinders are just a figment of the drive firmware's imagination. Sysinstall is even worse, since (IIRC) it *forces* cylinder alignment unless you select expert mode and type in the correct numbers. Marcel described the situation for gpart somewhere else in this thread. As for newfs, the defaults are fine as long as the filesystem doesn't fill up to the point where UFS starts using fragments - but when it does, you're in trouble anyway, so there's no point in overriding the defaults unless it makes sense for your data: a filesystem used mostly to store large files may benefit from increased block / fragment sizes, but remember to keep the 8:1 ratio. DES --=20 Dag-Erling Sm=C3=B8rgrav - des@des.no