Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933041Ab0LTSdH (ORCPT ); Mon, 20 Dec 2010 13:33:07 -0500 Received: from mail-iy0-f174.google.com ([209.85.210.174]:55485 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932742Ab0LTSdG convert rfc822-to-8bit (ORCPT ); Mon, 20 Dec 2010 13:33:06 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type:content-transfer-encoding; b=lP//XC+awXUkhl688zEB7wssUD+KZiL/5oh3O41Y5yCJskhYxv6vMDrwQYYuoZ+p6z azUr/zDQUh8QObDqRN+sE26OyqQgOXsUBd70l8tIRxZbKHanjP6boNbhGWZ7O5Bwzc5o jkEckevo7Eo6YrXZc7aDXM6yorDsKDL36Uq6M= MIME-Version: 1.0 In-Reply-To: <20101220190630.66084e1d@neptune.home> References: <20101220141553.GA6088@bitwizard.nl> <20101220190630.66084e1d@neptune.home> From: Greg Freemyer Date: Mon, 20 Dec 2010 13:32:44 -0500 Message-ID: Subject: Re: Slow disks. To: =?ISO-8859-1?Q?Bruno_Pr=E9mont?= Cc: Rogier Wolff , linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3033 Lines: 75 On Mon, Dec 20, 2010 at 1:06 PM, Bruno Pr?mont wrote: > Hi, > > [ccing linux-ide] > > Please provide the part of kernel log showing initialization of your > disk controller(s) as well as detection of all the discs. > Verbose lspci output for the disc controller and $(smartctl -i -A $disk) > output might be useful as well. > > Did you try the individual discs on a completely different system (e.g. > plain desktop system) and what revision of SATA are both components > supporting? > > Bruno > > > On Mon, 20 December 2010 Rogier Wolff wrote: >> Hi, >> >> A friend of mine has a server in a datacenter somewhere. His machine >> is not working properly: most of his disks take 10-100 times longer >> to process each IO request than normal. >> >> iostat -kx 10 output: >> Device: rrqm/s wrqm/s r/s ?w/s ?rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util >> sdd ? ? 0.30 ? 0.00 ? 0.40 1.20 2.80 ?1.10 ?4.88 ? ? 0.43 ?271.50 271.44 ?43.43 >> >> shows that in this 10 second period, the disk was busy for 4.3 seconds >> and serviced 15-16 requests during that time. >> >> Normal disks show "svctm" of around 10-20ms. >> >> Now you might say: It's his disk that's broken. >> Well no: I don't believe that all four of his disks are broken. >> (I just showed you output about one disk, but there are 4 disks in there >> all behaving similar, but some are worse than others.) >> >> Or you might say: It's his controller that's broken. So we thought >> too. We replaced the onboard sata controller with a 4-port sata >> card. Now they are running off the external sata card... Slightly >> better, but not by much. >> >> Or you might say: it's hardware. But suppose the disk doesn't properly >> transfer the data 9 times out of 10, wouldn't the driver tell us >> SOMETHING in the syslog that things are not fine and dandy? Moreover, >> In the case above, 12kb were transferred in 4.3 seconds. If CRC errors >> were happening, the interface would've been able to transfer over >> 400Mb during that time. So every transfer would need to be retried on >> average 30000 times... Not realistic. If that were the case, we'd >> surely hit a maximum retry limit every now and then? >> >> >> These syptoms started when the system was running 2.6.33, but are >> still present now the system has been upgraded to 2.6.36. >> >> Is there anything you can suggest to get to the root of this problem? >> Could this be a software issue with the driver? Can we enable some >> driver debugging to find out what is wrong? >> >> Any help will be appreciated. >> >> ? ? ? Roger. My personal guess would definitely be hardware. The only common component I can think of is power. SATA is very sensitive to requiring high-quality power. Much more so than IDE. Greg -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/