From owner-freebsd-questions@FreeBSD.ORG Wed Sep 21 10:41:25 2011 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 6577E1065672 for ; Wed, 21 Sep 2011 10:41:25 +0000 (UTC) (envelope-from m.seaman@infracaninophile.co.uk) Received: from smtp.infracaninophile.co.uk (smtp6.infracaninophile.co.uk [IPv6:2001:8b0:151:1:3fd3:cd67:fafa:3d78]) by mx1.freebsd.org (Postfix) with ESMTP id 8F5568FC08 for ; Wed, 21 Sep 2011 10:41:24 +0000 (UTC) Received: from seedling.black-earth.co.uk (seedling.black-earth.co.uk [81.187.76.163]) (authenticated bits=0) by smtp.infracaninophile.co.uk (8.14.5/8.14.5) with ESMTP id p8LAfFoX094008 (version=TLSv1/SSLv3 cipher=DHE-RSA-CAMELLIA256-SHA bits=256 verify=NO); Wed, 21 Sep 2011 11:41:15 +0100 (BST) (envelope-from m.seaman@infracaninophile.co.uk) X-DKIM: Sendmail DKIM Filter v2.8.3 smtp.infracaninophile.co.uk p8LAfFoX094008 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=infracaninophile.co.uk; s=201001-infracaninophile; t=1316601676; bh=+6cgG+njxo2aJkOV8Y9a4OZwE+jrZONhGzfm7iEZOB0=; h=Message-ID:Date:From:MIME-Version:To:CC:Subject:References: In-Reply-To:Content-Type:Cc:Content-Type:Date:From:In-Reply-To: Message-ID:Mime-Version:References:To; z=Message-ID:=20<4E79BF44.206@infracaninophile.co.uk>|Date:=20Wed,= 2021=20Sep=202011=2011:41:08=20+0100|From:=20Matthew=20Seaman=20|User-Agent:=20Mozilla/5.0=20(Macin tosh=3B=20Intel=20Mac=20OS=20X=2010.6=3B=20rv:6.0.2)=20Gecko/20110 902=20Thunderbird/6.0.2|MIME-Version:=201.0|To:=20Ross=20|CC:=20freebsd-questions@freebsd.org|Subject:=20Re:=2 0UFS=20journal=20size|References:=20|In-Reply-To:=20|X-Eni gmail-Version:=201.3.1|OpenPGP:=20id=3D60AE908C|Content-Type:=20mu ltipart/signed=3B=20micalg=3Dpgp-sha1=3B=0D=0A=20protocol=3D"appli cation/pgp-signature"=3B=0D=0A=20boundary=3D"------------enigE675F 24E571D1F9E8D92D284"; b=UaaW182kdpmdwZCkdcaLxhOhuuXogq0hZF9tiljqV+2YVH8z7lLbIjCiHOoqFvRu2 BbhEFk2yxP64XSORrcaFvWDbImCY0c0Asc8pzQg8jkUGhhPg8QoC8A62wwQDVrYOls 3tLRz0V6Hbp+sCVjbRcZIXgCfNxNbknvSzRB6U0I= Message-ID: <4E79BF44.206@infracaninophile.co.uk> Date: Wed, 21 Sep 2011 11:41:08 +0100 From: Matthew Seaman User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:6.0.2) Gecko/20110902 Thunderbird/6.0.2 MIME-Version: 1.0 To: Ross References: In-Reply-To: X-Enigmail-Version: 1.3.1 OpenPGP: id=60AE908C Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigE675F24E571D1F9E8D92D284" X-Virus-Scanned: clamav-milter 0.97.2 at lucid-nonsense.infracaninophile.co.uk X-Virus-Status: Clean X-Spam-Status: No, score=-0.1 required=5.0 tests=BAYES_20,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU autolearn=ham version=3.3.2 X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on lucid-nonsense.infracaninophile.co.uk Cc: freebsd-questions@freebsd.org Subject: Re: UFS journal size 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: Wed, 21 Sep 2011 10:41:25 -0000 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigE675F24E571D1F9E8D92D284 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 21/09/2011 10:48, Ross wrote: > Quoting the manpage: >=20 > -s jsize Specifies size of the journal if only one provider i= s > used for both data and journal. The default is = one > gigabyte. Size should be chosen based on provid= er's > load, and not on its size; recommended minimum i= s twice > the size of the physical memory installed. It i= s not > recommended to use gjournal for small file syste= ms > (e.g.: only few gigabytes big). >=20 > My question is: if I have 4 or 8 GB of RAM should I create 8 or even > 16 GB journals?.. This seems huge especially if the fs size without > journal is only 10 gigs. Or the recommended minimum is for systems low > on RAM? How much churn do you expect in the data on that partition? A journal that's about the same size as the actual filesystem in question and on the same physical device is not really going to get you any advantages. If it's mostly going to be read rather than written, then you wouldn't fill up that size of journal in any case. The 'twice physical RAM' advice is all about achieving maximum performance on large filesystems with lots of data writes: if write performance is not actually a limiting factor, then you could get away with a much smaller or even no journal at all. You might just as well use plain UFS+Softupdates. Softupdates to provide the meta-data ordering feature, so that if you do crash and need to fsck the filesystem, there's not going to be any really nasty stuff to fix. Plain UFS because a filesystem of that size will take about as long to fsck as it would to replay all the journalled but uncommitted updates. Cheers, Matthew --=20 Dr Matthew J Seaman MA, D.Phil. 7 Priory Courtyard Flat 3 PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate JID: matthew@infracaninophile.co.uk Kent, CT11 9PW --------------enigE675F24E571D1F9E8D92D284 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.16 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk55v0sACgkQ8Mjk52CukIyT2QCfYOs3JLgFKSChtskTMKNoCijv /wYAoIhh1ZrB4YNs/OjbDKvpzI7NMeqF =VT/b -----END PGP SIGNATURE----- --------------enigE675F24E571D1F9E8D92D284--