From owner-freebsd-questions@FreeBSD.ORG Wed Sep 21 16:11:27 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 45C651065673 for ; Wed, 21 Sep 2011 16:11:27 +0000 (UTC) (envelope-from djp@polands.org) Received: from cdptpa-omtalb.mail.rr.com (cdptpa-omtalb.mail.rr.com [75.180.132.122]) by mx1.freebsd.org (Postfix) with ESMTP id 02FF88FC18 for ; Wed, 21 Sep 2011 16:11:26 +0000 (UTC) Received: from hrndva-omtalb.mail.rr.com ([10.128.143.54]) by hrndva-qmta01.mail.rr.com with ESMTP id <20110921134121931.CWHP16315@hrndva-qmta01.mail.rr.com> for ; Wed, 21 Sep 2011 13:41:21 +0000 X-Authority-Analysis: v=1.1 cv=cSzO76bR5tCkfUT9bEmBgR3d7VUusRLeq08eKGxa4EU= c=1 sm=0 a=XYJHFtupD_QA:10 a=PmjUu4vlE_IA:10 a=kj9zAlcOel0A:10 a=IvncpQWizqU0KxmTkcmfsA==:17 a=pdJGPGiadrLIfjMDiWwA:9 a=CjuIK1q_8ugA:10 a=IvncpQWizqU0KxmTkcmfsA==:117 X-Cloudmark-Score: 0 X-Originating-IP: 67.52.213.147 Received: from [67.52.213.147] ([67.52.213.147:59408] helo=haran.polands.org) by hrndva-oedge04.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id 9F/91-05514-449E97E4; Wed, 21 Sep 2011 13:40:20 +0000 Received: from ararat.polands.org (ararat.polands.org [172.16.1.20]) by haran.polands.org (8.14.4/8.14.4) with ESMTP id p8LDeJZa032704; Wed, 21 Sep 2011 08:40:19 -0500 (CDT) (envelope-from djp@polands.org) Received: from ararat.polands.org (localhost [127.0.0.1]) by ararat.polands.org (8.14.4/8.14.4) with ESMTP id p8LDeJmZ048881; Wed, 21 Sep 2011 08:40:19 -0500 (CDT) (envelope-from djp@ararat.polands.org) Received: (from djp@localhost) by ararat.polands.org (8.14.4/8.14.4/Submit) id p8LDeI2I048880; Wed, 21 Sep 2011 08:40:18 -0500 (CDT) (envelope-from djp) Date: Wed, 21 Sep 2011 08:40:18 -0500 From: Doug Poland To: Ross Message-ID: <20110921134018.GA48785@polands.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) 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 16:11:27 -0000 On Wed, Sep 21, 2011 at 12:48:25PM +0300, Ross wrote: > Quoting the manpage: > > -s jsize Specifies size of the journal if only one provider is > used for both data and journal. The default is one > gigabyte. Size should be chosen based on provider's > load, and not on its size; recommended minimum is twice > the size of the physical memory installed. It is not > recommended to use gjournal for small file systems > (e.g.: only few gigabytes big). > > 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? > My experience has shown that speed of the underlying filessystem has a huge impact on the required size of the journal. I have a system running hardware RAID-10 on a 3Ware SATA controller. On a 100G partition, rsync would regularly cause a panic until I got my journal up above 10G. This particular host has only 1G of RAM and a single 3.4GHz P4 CPU. Sizing this particular box using gjournal was painful until I got the journal sizes large enough. It turns out the journals had to be so large (for the infrequent write burst) that a significant amount of disk was chewed up for journals that were mostly unused. If I had to do it over again, I would have not used gjournal and simply used softupdates. YMMV -- Regards, Doug