Received: from localhost (maia-1.hub.org [200.46.204.191]) by postgresql.org (Postfix) with ESMTP id BF54B9FB464 for ; Mon, 25 Jun 2007 07:01:54 -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 40822-06 for ; Mon, 25 Jun 2007 07:01:46 -0300 (ADT) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.5 Received: from nz-out-0506.google.com (nz-out-0506.google.com [64.233.162.233]) by postgresql.org (Postfix) with ESMTP id F220D9FB450 for ; Mon, 25 Jun 2007 07:01:45 -0300 (ADT) Received: by nz-out-0506.google.com with SMTP id m22so1120577nzf for ; Mon, 25 Jun 2007 03:01:44 -0700 (PDT) DKIM-Signature: a=rsa-sha1; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; b=W0b1VORkZW1QcFoZonEE/ieNkr+sXDFyoYaXck1ogCiwJO6i0ADgkPV2g5BB4xWu8dj6tYsxInqOlMguY155Qj8FvG5SHphm2TXzha5bjsCFWyjziC+aPwcfDXpHGd3ZKY5jQczlafmxOXeoiQbpye99YGVLMMZofjMjvij0xS4= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; b=nALjJYg5o9V95NEtCUMqfSYxTCaPfdReCFZs6MBk7Tfb8uhlBSd8nxc81IgzGoghuLRRlxbNNP+0fzPtMoklFW7zAJupRYJYU+esD0562c+tIRQVA968Jx0942/ZYZc/jrb6QUpLQT0t/gVMn1IL/T/jcVmXYg9HJIcF7WROZs8= Received: by 10.114.157.1 with SMTP id f1mr5281002wae.1182765704502; Mon, 25 Jun 2007 03:01:44 -0700 (PDT) Received: by 10.115.90.9 with HTTP; Mon, 25 Jun 2007 03:01:44 -0700 (PDT) Message-ID: <758d5e7f0706250301s65a39f29ya960ddb3ab5fa692@mail.gmail.com> Date: Mon, 25 Jun 2007 12:01:44 +0200 From: "Dawid Kuroczko" To: "Postgresql Performance" Subject: Is AIX Concurrent IO safe with PostgreSQL? MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200706/563 X-Sequence-Number: 25596 Hello, I am wondering if it is safe to assume that specifying cio mount option is safe with PostgreSQL. As far as I understand the CIO (AIX Concurrent I/O) means that filesystem does not serialize access to file blocks. In other words multiple threads can simultaneously read and write the file block, which means that it is possible that reader reads stale data. Now, if database enforces its own serialization (and as far as I can tell, bufmgr does it exactly), this option should be totally safe to use, probably giving boost since kernel has less overhead while multiple processes access the database file. Is my thinking correct? Regards, Dawid