X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (unknown [200.46.204.144]) by svr1.postgresql.org (Postfix) with ESMTP id 1B3DC52862 for ; Mon, 23 May 2005 19:23:50 -0300 (ADT) Received: from svr1.postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 28747-10 for ; Mon, 23 May 2005 22:23:48 +0000 (GMT) Received: from server07.icaen.uiowa.edu (server07.icaen.uiowa.edu [128.255.17.47]) by svr1.postgresql.org (Postfix) with ESMTP id 8E2FC52812 for ; Mon, 23 May 2005 19:23:47 -0300 (ADT) Received: from server11.icaen.uiowa.edu (server11.icaen.uiowa.edu [128.255.17.51]) by server07.icaen.uiowa.edu (8.13.3/8.12.9) with ESMTP id j4NMNk5l004989; (envelope-from ) Mon, 23 May 2005 17:23:46 -0500 (CDT) Received: from [192.168.1.11] (12-215-118-172.client.mchsi.com [12.215.118.172]) (authenticated user=jfmeinel) by server11.icaen.uiowa.edu (8.13.2/smtp-serv-1.7) with ESMTP id j4NMNjI7010569 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256); (envelope-from ) Mon, 23 May 2005 17:23:46 -0500 (CDT) Message-ID: <429257ED.6020004@arbash-meinel.com> Date: Mon, 23 May 2005 17:23:41 -0500 From: John A Meinel User-Agent: Mozilla Thunderbird 1.0.2-1.3.3 (X11/20050513) X-Accept-Language: en-us, en MIME-Version: 1.0 To: David Parker Cc: pgsql-performance@postgresql.org Subject: Re: seqential vs random io References: <07FDEE0ED7455A48AC42AC2070EDFF7C746598@corpsrv2.tazznetworks.com> In-Reply-To: <07FDEE0ED7455A48AC42AC2070EDFF7C746598@corpsrv2.tazznetworks.com> X-Enigmail-Version: 0.91.0.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigA506A3286E2A046E328BFC44" X-Virus-Scanned: ClamAV version 0.83, clamav-milter version 0.83 on clamav.icaen.uiowa.edu X-Virus-Scanned: ClamAV version 0.83, clamav-milter version 0.83 on clamav.icaen.uiowa.edu X-Virus-Status: Clean X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, hits=0 tagged_above=0 required=5 tests= X-Spam-Level: X-Archive-Number: 200505/350 X-Sequence-Number: 12514 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigA506A3286E2A046E328BFC44 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit David Parker wrote: > I just got a question from one our QA guys who is configuring a RAID 10 > disk that is destined to hold a postgresql database. The disk > configuration procedure is asking him if he wants to optimize for > sequential or random access. My first thought is that random is what we > would want, but then I started wondering if it's not that simple, and my > knowledge of stuff at the hardware level is, well, limited..... > > If it were your QA guy, what would you tell him? > > - DAP Random. Sequential is always pretty fast, it is random that hurts. The only time I would say sequential is if you were planning on streaming large files (like iso images) with low load. But for a DB, even a sequential scan will probably not be that much data. At least, that's my 2c. John =:-> --------------enigA506A3286E2A046E328BFC44 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (GNU/Linux) Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org iD8DBQFCklfvJdeBCYSNAAMRAn2WAJ41931HS6qX76S/d6ZdfEv5MyC+QwCeJC6R Kwt2q1dJb0ykrw9oJwuxW00= =qS7/ -----END PGP SIGNATURE----- --------------enigA506A3286E2A046E328BFC44--