From owner-freebsd-stable@FreeBSD.ORG Sun Nov 25 16:08:10 2007 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 9254216A420; Sun, 25 Nov 2007 16:08:10 +0000 (UTC) (envelope-from espen@modula.no) Received: from mx2.modula.no (mx2.modula.no [193.142.30.42]) by mx1.freebsd.org (Postfix) with ESMTP id 46D7D13C465; Sun, 25 Nov 2007 16:08:09 +0000 (UTC) (envelope-from espen@modula.no) Received: from localhost (unknown [193.142.30.42]) by mx2.modula.no (Postfix) with ESMTP id 0A858FD000C; Sun, 25 Nov 2007 17:06:12 +0100 (CET) Received: from mx2.modula.no ([193.142.30.42]) by localhost (mx2.modula.no [193.142.30.42]) (amavisd-new, port 10024) with ESMTP id BlEjywLIMGzb; Sun, 25 Nov 2007 17:06:09 +0100 (CET) Received: from smtp.modula.no (smtp.modula.no [193.142.30.47]) by mx2.modula.no (Postfix) with ESMTP id 66B26FD0003; Sun, 25 Nov 2007 17:06:09 +0100 (CET) Received: from espen-tagestads-computer.local (smtp.modula.no [193.142.30.47]) by smtp.modula.no (Postfix) with ESMTP id 53895170001; Sun, 25 Nov 2007 17:19:33 +0100 (CET) Message-ID: <47499E65.4050206@modula.no> Date: Sun, 25 Nov 2007 17:10:13 +0100 From: Espen Tagestad User-Agent: Thunderbird 2.0.0.9 (Macintosh/20071031) MIME-Version: 1.0 To: Tom Judge References: <47496BE1.8080206@modula.no> <47499710.1050402@tomjudge.com> In-Reply-To: <47499710.1050402@tomjudge.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-stable@freebsd.org, freebsd-hardware@freebsd.org Subject: Re: SAS5IR performance issue with Dell 860 X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 25 Nov 2007 16:08:10 -0000 Tom Judge wrote: > Espen Tagestad wrote: >> We recently bought 3 new Dell 860 servers with the onboard SAS5/IR >> SATA RAID-controller. They seem to be quite well spec'ed servers with >> management and everything - but I am experiencing av major performance >> issue with the disc i/o. On write I get at max 7-8MB/sec, while read >> gives a bit more (11MB/sec). I tried first with 6.2-RELEASE, and then >> upgraded to 6.3-PRERELEASE without any better results. > > You will also need to set the hw.mpt.enable_sata_wc sysctl in loader.conf. There isn't any hw.mpt.enable_sata_wc sysctl available on my systems. It is 6.3-PRERELEASE, but as I recon there wasn't any *mpt* sysctls on the latest 6.2-RELEASE either. Is it deprecated? Is there any other options? I can see a hw.ata.wc but that one is set to 1 which I presume equals enabled. Anyway - the write cache, is that something that is set on the raid controller, or is it a buffer in the FreeBSD kernel that takes care of the caching? As the commit note you sent me said - to ensure absolutely best data integrity the write cache should be left switched off. But write performance of 7-8MB/sec is just too low for that - is the controller /sata drives really that slow? -- med vennlig hilsen / with regards, Espen Tagestad