Received: from localhost (maia-1.hub.org [200.46.204.191]) by postgresql.org (Postfix) with ESMTP id DCEFA9FA683 for ; Thu, 16 Aug 2007 14:53:54 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.191]) (amavisd-maia, port 10024) with ESMTP id 25595-07 for ; Thu, 16 Aug 2007 14:53:54 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from exprod6og56.obsmtp.com (exprod6og56.obsmtp.com [64.18.1.208]) by postgresql.org (Postfix) with SMTP id 2CDCA9FA5A2 for ; Thu, 16 Aug 2007 14:53:53 -0300 (ADT) Received: from source ([63.240.6.47]) (using TLSv1) by exprod6ob56.postini.com ([64.18.5.12]) with SMTP; Thu, 16 Aug 2007 10:53:48 PDT Received: from 172.16.1.25 by mail.Mi8.com with ESMTP (- Welcome to Mi8 Corporation www.Mi8.com (D1)); Thu, 16 Aug 2007 13:54:12 -0400 X-Server-Uuid: 0764DD54-627B-4C45-B37D-789FBDEDA467 Received: from MI8NYCMAIL08.Mi8.com ([172.16.1.164]) by D01HOST03.Mi8.com with Microsoft SMTPSVC(6.0.3790.1830); Thu, 16 Aug 2007 13:54:04 -0400 Received: from 75.209.77.228 ([75.209.77.228]) by MI8NYCMAIL08.Mi8.com ( [172.16.1.190]) via Exchange Front-End Server mi8owa.mi8.com ( [172.16.1.107]) with Microsoft Exchange Server HTTP-DAV ; Thu, 16 Aug 2007 17:53:35 +0000 User-Agent: Microsoft-Entourage/11.3.6.070618 Date: Thu, 16 Aug 2007 10:53:00 -0700 Subject: Re: Integrated perc 5/i From: "Luke Lonergan" To: "Michael Ben-Nes" , "PostgreSQL Performance" Message-ID: Thread-Topic: [PERFORM] Integrated perc 5/i Thread-Index: AcfgLkjth5/v6EwhEdy3gAAbY5GgAQ== In-Reply-To: MIME-Version: 1.0 X-OriginalArrivalTime: 16 Aug 2007 17:54:04.0007 (UTC) FILETIME=[6F145770:01C7E02E] X-WSS-ID: 6ADA50B02X44152463-10-01 Content-Type: multipart/alternative; boundary=B_3270106381_70246 X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200708/163 X-Sequence-Number: 26293 > This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. --B_3270106381_70246 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Hi Michael, There is a problem with some Dell =B3perc 5=B2 RAID cards, specifically we=B9ve had this problem with the 2950 as of 6 months ago =AD they do not support RAID10. They have a setting that sounds like RAID10, but it actually implements spanning of mirrors. This means that you will not get more than one disk worth of performance whether you are performing random seeks (within a one disk sized area) or sequential transfers. I recommend you read the section in the Dell configuration guide very carefully and look for supplemental sources of technical information about it. We found the issue clearly explained in a Dell technical memo that I don=B9t have in front of me =AD we were shocked to find this out. As suggested =AD the RAID5 numbers from these controllers are very strong. - Luke On 8/16/07 1:26 AM, "Michael Ben-Nes" wrote: > Hi >=20 > I wanted to know if the integrated perc 5/i which come with Dell 2950 wil= l > yield maximum performance from RAID 10 ( 15K SAS ). > Or should I ask for different card ? >=20 > I read an old post that shows that RAID 10 does not work eficently under = perc > 5/i=20 > http://groups.google.com/group/pgsql.performance/browse_thread/thread/b85= 926fe > 6de1f6c2/38837995887b6033?lnk=3Dst&q=3Dperc+5%2Fi+performance&rnum=3D6&hl=3Den#38= 83799 > 5887b6033 =20 > e6de1f6c2/38837995887b6033?lnk=3Dst&q=3Dperc+5%2Fi+performance&rnum=3D6= & > hl=3Den#38837995887b6033> >=20 > Does any one have any experience with RAID 10 & perc 5/i ? >=20 > Thanks, > Miki --B_3270106381_70246 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Re: [PERFORM] Integrated perc 5/i Hi Mi= chael,

There is a problem with some Dell “perc 5” RAID cards, specific= ally we’ve had this problem with the 2950 as of 6 months ago – t= hey do not support RAID10.  They have a setting that sounds like RAID10= , but it actually implements spanning of mirrors.  This means that you = will not get more than one disk worth of performance whether you are perform= ing random seeks (within a one disk sized area) or sequential transfers.

I recommend you read the section in the Dell configuration guide very caref= ully and look for supplemental sources of technical information about it. &n= bsp;We found the issue clearly explained in a Dell technical memo that I don= ’t have in front of me – we were shocked to find this out.

As suggested – the RAID5 numbers from these controllers are very stro= ng.

- Luke


On 8/16/07 1:26 AM, "Michael Ben-Nes" <miki@epoch.co.il> wr= ote:

Hi

I wanted to know if the integrated perc 5/i which come with Dell 2950 will = yield maximum performance from RAID 10 ( 15K SAS ).
Or should I ask for different card ?

I read an old post that shows that RAID 10 does not work eficently under pe= rc 5/i
http://groups.google.com/group/pgsql.performance/br= owse_thread/thread/b85926fe6de1f6c2/38837995887b6033?lnk=3Dst&q=3Dperc+5%2Fi= +performance&rnum=3D6&hl=3Den#38837995887b6033  <http://groups.google.com/group/pgsql.performance/br= owse_thread/thread/b85926fe6de1f6c2/38837995887b6033?lnk=3Dst&amp;q=3Dperc+5= %2Fi+performance&amp;rnum=3D6&amp;hl=3Den#38837995887b6033>

Does any one have any experience with RAID 10 & perc 5/i ?

Thanks,
Miki

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