Received: from localhost (unknown [200.46.204.183]) by developer.postgresql.org (Postfix) with ESMTP id E62722E0033 for ; Tue, 8 Apr 2008 16:24:15 -0300 (ADT) Received: from developer.postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 25483-07 for ; Tue, 8 Apr 2008 16:24:11 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from mailsrv1.zmi.at (mailsrv1.zmi.at [212.69.162.198]) by developer.postgresql.org (Postfix) with ESMTP id A0BDB2E002C for ; Tue, 8 Apr 2008 16:24:11 -0300 (ADT) Received: from mailsrv.i.zmi.at (h081217054243.dyn.cm.kabsi.at [81.217.54.243]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mailsrv.i.zmi.at", Issuer "mailsrv.i.zmi.at" (not verified)) by mailsrv1.zmi.at (Postfix) with ESMTP id 0FA76CD7; Tue, 8 Apr 2008 21:24:08 +0200 (CEST) Received: from saturn.i.zmi.at (saturn.i.zmi.at [10.0.0.2]) by mailsrv.i.zmi.at (Postfix) with ESMTP id B0988BFB4; Tue, 8 Apr 2008 21:23:35 +0200 (CEST) From: Michael Monnerie Organization: it-management http://it-management.at To: Johann Spies , pgsql-admin@postgresql.org Subject: Re: Handling large volumes of data Date: Tue, 8 Apr 2008 21:24:07 +0200 User-Agent: KMail/1.9.6 (enterprise 20070904.708012) References: <20080408094233.GG13409@sun.ac.za> <200804081201.15175@zmi.at> <20080408101336.GJ13409@sun.ac.za> In-Reply-To: <20080408101336.GJ13409@sun.ac.za> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart1241037.Ls2WfBh3bK"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit Message-Id: <200804082124.07687@zmi.at> X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0.023 tagged_above=0 required=5 tests=AWL=0.023 X-Spam-Level: X-Archive-Number: 200804/81 X-Sequence-Number: 28845 --nextPart1241037.Ls2WfBh3bK Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline On Dienstag, 8. April 2008 Johann Spies wrote: > I have got 8x720G disks in a hardware raid 5 setup. It is a Dell 2950 > server. I am using an XFS-filesystem. =A0I am not certain about the > speed of the hard disk, but we bought the fastest we could get. 720G looks like SATA disks, probably with "only" 7.200rpm. The Western=20 Digital Raptor with 10.000rpm are about twice as fast on random access.=20 Also, RAID5/6 are very,very slow when it comes to small disk *writes*.=20 Which is exactly what a db makes. Retry with RAID-10, and you'll see=20 the difference. We've had 6 WD Raptors in RAID-6 on an Areca RAID, and changed it to 8x=20 Raptor RAID-10, that improved things. mfg zmi =2D-=20 // Michael Monnerie, Ing.BSc ----- http://it-management.at // Tel: 0676/846 914 666 .network.your.ideas. // PGP Key: "curl -s http://zmi.at/zmi.asc | gpg --import" // Fingerprint: AC19 F9D5 36ED CD8A EF38 500E CE14 91F7 1C12 09B4 // Keyserver: www.keyserver.net Key-ID: 1C1209B4 --nextPart1241037.Ls2WfBh3bK Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.4-svn0 (GNU/Linux) iD8DBQBH+8ZXzhSR9xwSCbQRAiLRAKCKfUr1f8L2O8ZNNP7EYkmNJvG3rQCfZA78 hQxE8XQ2RNXqfPTQpBXQ9AE= =5g+d -----END PGP SIGNATURE----- --nextPart1241037.Ls2WfBh3bK--