From owner-freebsd-questions@FreeBSD.ORG Thu Jun 17 15:51:30 2010 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 886A8106567A for ; Thu, 17 Jun 2010 15:51:30 +0000 (UTC) (envelope-from freebsd@optiksecurite.com) Received: from relais.videotron.ca (relais.videotron.ca [24.201.245.36]) by mx1.freebsd.org (Postfix) with ESMTP id 5B4188FC20 for ; Thu, 17 Jun 2010 15:51:30 +0000 (UTC) MIME-version: 1.0 Received: from [69.69.69.193] ([69.70.93.206]) by VL-MH-MR002.ip.videotron.ca (Sun Java(tm) System Messaging Server 6.3-4.01 (built Aug 3 2007; 32bit)) with ESMTP id <0L46000JC1DS3X40@VL-MH-MR002.ip.videotron.ca> for freebsd-questions@freebsd.org; Thu, 17 Jun 2010 11:51:28 -0400 (EDT) Message-id: <4C1A4488.2010908@optiksecurite.com> Date: Thu, 17 Jun 2010 11:51:36 -0400 From: Martin Turgeon User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; fr; rv:1.9.1.9) Gecko/20100317 Thunderbird/3.0.4 To: freebsd-questions@freebsd.org Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7BIT X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Subject: Optimal RAID10 config on PERC6 (cache question) 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: Thu, 17 Jun 2010 15:51:30 -0000 Hi everyone, I got 2 brand new Dell R510 with 4x146 SAS 10K RPM connected to the PERC6 RAID adapter in a RAID10 configuration. Those servers are mostly going to be used for a master/master MySQL replication. Both are running 8.0-REL amd64. When I took a look at the 'mfiutil' command to make a script to detect RAID failure I saw that the cache were disabled on the volume: (those are all Dell's default) db1# mfiutil show volumes mfi0 Volumes: Id Size Level Stripe State Cache Name mfid0 ( 272G) RAID-10 64K OPTIMAL Disabled db1# mfiutil cache mfid0 mfi0 volume mfid0 cache settings: I/O caching: disabled write caching: write-back read ahead: none drive write cache: default I read in the man page of mfiutil that "drive write cache" is the cache on the physical drive which should be disable for data integrity. My first question is: Is the 'default' to disable the physical drive cache or should I modify it explicitly to disable? I configured 'innodb_flush_method=O_DIRECT' in my.cnf to maximize performance, but I read that this option should only be used with a battery backed up RAID card. My PERC6 got a battery but I'm wondering if the current setting for my cache are using it correctly? Can someone explain me the differences between the cache types? My main concern is data integrity in case of hardware or power failures. What would be the optimal configuration in that case. Thanks in advance for your clever insights, Martin ** **