From owner-freebsd-hardware@FreeBSD.ORG Sun Nov 25 16:02:54 2007 Return-Path: Delivered-To: freebsd-hardware@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id E48F316A418 for ; Sun, 25 Nov 2007 16:02:54 +0000 (UTC) (envelope-from tom@tomjudge.com) Received: from smtp808.mail.ird.yahoo.com (smtp808.mail.ird.yahoo.com [217.146.188.68]) by mx1.freebsd.org (Postfix) with SMTP id 5849E13C442 for ; Sun, 25 Nov 2007 16:02:53 +0000 (UTC) (envelope-from tom@tomjudge.com) Received: (qmail 84940 invoked from network); 25 Nov 2007 15:36:13 -0000 Received: from unknown (HELO ?192.168.1.2?) (thomasjudge@btinternet.com@86.139.146.42 with plain) by smtp808.mail.ird.yahoo.com with SMTP; 25 Nov 2007 15:36:13 -0000 X-YMail-OSG: P2nvt9kVM1nvI_dxGqrhaFY9BjHcXlvYFrDSKBjldFV_4lko Message-ID: <47499710.1050402@tomjudge.com> Date: Sun, 25 Nov 2007 15:38:56 +0000 From: Tom Judge User-Agent: Thunderbird 1.5.0.13 (X11/20070824) MIME-Version: 1.0 To: Espen Tagestad References: <47496BE1.8080206@modula.no> In-Reply-To: <47496BE1.8080206@modula.no> 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-hardware@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: General discussion of FreeBSD hardware List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 25 Nov 2007 16:02:55 -0000 Espen Tagestad wrote: > Hi, > > 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. > > I am aware of some discussion around this issue on these two maillists > in the spring earlier on this year, but I have not been able to find any > good resolution. My old firewall/router at home equipped with a 733Mhz > Pentium 3 processor and a old 40GB IDE harddrive made around year 2001 > performe better. Is there anybody out there with the same problem who > has solved this issue? Could it be that this is solved in 7.0? > > Thanks in advance. > Hi, If you have sata disks on this controller you will need to run RELENG_6 dated after 2007-06-05 21:32:57. You will also need to set the hw.mpt.enable_sata_wc sysctl in loader.conf. Here is Scott Long's commit log of the changes that 'fix' this issue. Tom Commit Message: scottl 2007-06-03 23:13:05 UTC FreeBSD src repository Modified files: sys/dev/mpt mpt.c mpt.h mpt_cam.c Log: mpt.c: mpt.h: Add support for reading extended configuration pages. mpt_cam.c: Do a top level topology scan on the SAS controller. If any SATA device are discovered in this scan, send a passthrough FIS to set the write cache. This is controllable through the following tunable at boot: hw.mpt.enable_sata_wc: -1 = Do not configure, use the controller default 0 = Disable the write cache 1 = Enable the write cache The default is -1. This tunable is just a hack and may be deprecated in the future. Turning on the write cache alleviates the write performance problems with SATA that many people have observed. It is not recommend for those who value data reliability! I cannot stress this strongly enough. However, it is useful in certain circumstances, and it brings the performence in line with what a generic SATA controller running under the FreeBSD ATA driver provides (and the ATA driver has had the WC enabled by default for years).