From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id q73BSTpa088411 for ; Fri, 3 Aug 2012 06:28:29 -0500 Received: from greer.hardwarefreak.com (mo-65-41-216-221.sta.embarqhsd.net [65.41.216.221]) by cuda.sgi.com with ESMTP id tCLj45WquCDhF3VC for ; Fri, 03 Aug 2012 04:28:28 -0700 (PDT) Message-ID: <501BB5DD.1000302@hardwarefreak.com> Date: Fri, 03 Aug 2012 06:28:29 -0500 From: Stan Hoeppner MIME-Version: 1.0 Subject: Re: realtime section bugs still around References: <20120730030333.GE2877@dastard> <50186E51.1020107@hardwarefreak.com> <5018A8C7.8050406@hardwarefreak.com> <5019CC34.5050003@hardwarefreak.com> <501A58DB.7070801@hardwarefreak.com> In-Reply-To: <501A58DB.7070801@hardwarefreak.com> Reply-To: stan@hardwarefreak.com List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: stan@hardwarefreak.com Cc: Jason Newton , xfs@oss.sgi.com On 8/2/2012 5:39 AM, Stan Hoeppner wrote: > We already gave you the biggest cause of your latency, which is garbage > collection/wear leveling. You can't see inside the SSDs, but you can > see the latency jump with either top (%wa) or iostat (await, > milliseconds). Run > > iostat -x -d 1 20 > > and you get 20 reports 1 second apart. 1s is minimum granularity. This > should clearly show the latency spikes caused by the SSDs. Maybe even > execute it for 60 seconds and pipe to a file. The above assumes Linux can see the individual devices. I've never used Intel's fakeraid. If its driver presents a single device to the kernel instead of both SSD devices, iostat won't show which SSD's garbage collection is kicking in and/or when. It would be most beneficial if you could see the iostat data for both SSD devices as it would tell you exactly when each drive's GC/leveling kicks in. If the Intel fakeraid doesn't allow you to see both devices, you'll need to switch to md/RAID. I'm sure that will be problematic as you're very likely booting from the Intel RAIDed SSD device. -- Stan _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs