From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751306AbZJPWlU (ORCPT ); Fri, 16 Oct 2009 18:41:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750897AbZJPWlT (ORCPT ); Fri, 16 Oct 2009 18:41:19 -0400 Received: from mail-gx0-f216.google.com ([209.85.217.216]:50070 "EHLO mail-gx0-f216.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750838AbZJPWlT convert rfc822-to-8bit (ORCPT ); Fri, 16 Oct 2009 18:41:19 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=R9tpr9SIPCmIiq//5wwEVYJogADXftxiDNbRuGNpbHorGSzpbwlbcbs+r/jF/b0NS5 hikPzgnpyFnbp+FQ3jz2wExwfXkKe9VR6IwcjxPUVr3qj6dH8BbsFiu78B9YuDOgpQ2b B6zbU9EpI+PnVnnyIeUL4iGmyFo++c4xuO/ZQ= MIME-Version: 1.0 In-Reply-To: References: Date: Fri, 16 Oct 2009 15:36:13 -0700 Message-ID: Subject: Re: 3ware 9650SE-4PML RAID-1 Question: One reader process starves I/O to the rest of the system? From: adam radford To: Justin Piszcz Cc: linux-kernel@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 Justin, Can you try turning down the queue depth of the disk that is getting written to to see if that resolves your responsiveness issue? I.E.: echo "16" > /sys/block/sdX/device/queue_depth (replace X with disk letter of device from /raid6 mountpoint). FYI: It's probably better to send questions like this to linux-scsi rather than linux-kernel. -Adam On Fri, Oct 16, 2009 at 2:46 PM, Justin Piszcz wrote: > Hello, > > I tried CFQ/deadline schedulers, when I run the following: > > # /usr/bin/time dd if=/dev/sdb2 of=/raid6/sdb2.img > > Behind which are 2 x Raptor 150GB disks, the system is pretty much unusable > when I control-c the dd, it comes back to life. > > The RAID-6 is a 15-disk RAID-6 which does 600-700MB/s writes. > > All cards are on PCI-e and have adequate bandwidth on a P55 board (DP55KG). > > Are there any recommended tuning options for a RAID-1 configuration, such > that > a heavy I/O read or write operation does not pause the system? > > During the dd.. > > Drive Performance Monitor Configuration for /c1 ... > Performance Monitor: ON > Version: 1 > Max commands for averaging: 100 > Max latency commands to save: 10 > Requested data: Instantaneous Drive Statistics > >                               Queue           Xfer         Resp > Port   Status           Unit   Depth   IOPs    Rate(MB/s)   Time(ms) > ------------------------------------------------------------------------ > p0     OK               u0     25      762     26.219       19 p1     OK >           u0     23      780     25.953       24 p2     OK               u1 >     1       0       0.000        98 p3     NOT-PRESENT      -      -       - >       -            - > > Justin. > > > -- > 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/ >