From owner-freebsd-current@FreeBSD.ORG Thu Jan 29 14:48:57 2009 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 0D621106566B for ; Thu, 29 Jan 2009 14:48:57 +0000 (UTC) (envelope-from olli@lurza.secnetix.de) Received: from lurza.secnetix.de (unknown [IPv6:2a01:170:102f::2]) by mx1.freebsd.org (Postfix) with ESMTP id 80FAF8FC08 for ; Thu, 29 Jan 2009 14:48:56 +0000 (UTC) (envelope-from olli@lurza.secnetix.de) Received: from lurza.secnetix.de (localhost [127.0.0.1]) by lurza.secnetix.de (8.14.3/8.14.3) with ESMTP id n0TEmmR3061259; Thu, 29 Jan 2009 15:48:49 +0100 (CET) (envelope-from oliver.fromme@secnetix.de) Received: (from olli@localhost) by lurza.secnetix.de (8.14.3/8.14.3/Submit) id n0TEmmiO061258; Thu, 29 Jan 2009 15:48:48 +0100 (CET) (envelope-from olli) Date: Thu, 29 Jan 2009 15:48:48 +0100 (CET) Message-Id: <200901291448.n0TEmmiO061258@lurza.secnetix.de> From: Oliver Fromme To: freebsd-current@FreeBSD.ORG, ptice@aldridge.com In-Reply-To: X-Newsgroups: list.freebsd-current User-Agent: tin/1.8.3-20070201 ("Scotasay") (UNIX) (FreeBSD/6.4-PRERELEASE-20080904 (i386)) MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-2.1.2 (lurza.secnetix.de [127.0.0.1]); Thu, 29 Jan 2009 15:48:49 +0100 (CET) Cc: Subject: Re: Help me select hardware....Some real world data that might help X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: freebsd-current@FreeBSD.ORG, ptice@aldridge.com List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 29 Jan 2009 14:48:57 -0000 Paul Tice wrote: > I just bumped up the kmem, arc.max, enabled zil and reenabled > mdcomp. Prefetch is disabled. Less than 1 minute into a backup > run of only 4 machines, I've got a fresh ZFS wedgie. How exactly did you bump up kmem? As far as I know, it is not necessary anymore on 8-current/amd64, because the defaults are already much larger. In fact it might be possible that your tuning made things worse. > As I understand it, the ZIL is not as much of an integrity boost as > a speed boost, especially since we already have checksum-per-block. The checksum feature works purely on a block level, while the intent log (ZIL) records certain changes to meta data on the file system, similar to a journal, which can be used for recovery after a crash (power outage, hardware failure, kernel panic, human error). Both features are completely orthogonal, one cannot replace the other. Therefore I recommend to keep the ZIL enabled. Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M. Handelsregister: Registergericht Muenchen, HRA 74606, Geschäftsfuehrung: secnetix Verwaltungsgesellsch. mbH, Handelsregister: Registergericht Mün- chen, HRB 125758, Geschäftsführer: Maik Bachmann, Olaf Erb, Ralf Gebhart FreeBSD-Dienstleistungen, -Produkte und mehr: http://www.secnetix.de/bsd "In My Egoistical Opinion, most people's C programs should be indented six feet downward and covered with dirt." -- Blair P. Houghton