From mboxrd@z Thu Jan 1 00:00:00 1970 From: Art Wildman Subject: Re: High iowait Date: Thu, 24 Aug 2006 16:06:16 -0400 Message-ID: <44EE06B8.70304@noaa.gov> References: <3a1eedb70608211931w67f86bccpb383bb0ff8089f45@mail.gmail.com> <200608221138.15159.mail@lobraun.de> <3a1eedb70608230910u34ce5e96hf36f25f0ff560ea4@mail.gmail.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7BIT Return-path: In-reply-to: <3a1eedb70608230910u34ce5e96hf36f25f0ff560ea4@mail.gmail.com> Sender: linux-config-owner@vger.kernel.org List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: jassduec@gmail.com Cc: Lothar Braun , linux-admin@vger.kernel.org, linux-config@vger.kernel.org jassduec@gmail.com wrote: > Basically i am not able to achieve the kind of throughput which i > should get from my RAID system. And i think the OS is the culprit > (some bug in the vendor kernel) since for some reason it goes into > huge iowaits preventing the applications to read/write more data. How > can i debug whether the problem is with the OS or with the device? > #1 Problem usually: Is DMA enabled? (see hdparm refs)... RAID FAQ & Docs... http://www.faqs.org/contrib/linux-raid/x37.html http://www.redhat.com/docs/manuals/enterprise/RHEL-4-Manual/sysadmin-guide/ch-raid-intro.html http://www.linuxhomenetworking.com/wiki/index.php/Quick_HOWTO_:_Ch26_:_Linux_Software_RAID http://www.tldp.org/HOWTO/Software-RAID-HOWTO.html mdadm - tool for managing Linux Software RAID arrays http://neil.brown.name/blog/mdadm Benchmarking RAID configurations http://www.catux.org/index.php?contingut=articles&num=101 http://www.acnc.com/benchmarks.html http://www.coker.com.au/bonnie++/ http://www.iozone.org/ http://www.sourcepole.com/sources/reviews/raid/bottom.html HOWTO Use hdparm to improve IDE device performance - GentooWiki http://gentoo-wiki.com/HOWTO_Use_hdparm_to_improve_IDE_device_performance HDparm - Tuning up your IDE hard disks using hdparm. http://usalug.org/phpBB2/viewtopic.php?p=33142 -GL Art@JAX -- Art Wildman - NWS JAX FL. - http://www.srh.noaa.gov/jax "If you choose not to decide, you still have made a choice" -Rush|Freewill