Received: from localhost (maia-4.hub.org [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id D154A9FB599 for ; Wed, 9 May 2007 14:01:54 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 93463-05-2 for ; Wed, 9 May 2007 14:01:51 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from lists.commandprompt.com (host-254.commandprompt.net [207.173.203.254]) by postgresql.org (Postfix) with ESMTP id E00889FA434 for ; Wed, 9 May 2007 14:01:50 -0300 (ADT) Received: from perhan.alvh.no-ip.org (201-221-217-243.bk12-dsl.surnet.cl [201.221.217.243]) (authenticated bits=0) by lists.commandprompt.com (8.13.7/8.13.6) with ESMTP id l49H1mrj002897; Wed, 9 May 2007 10:01:49 -0700 Received: by perhan.alvh.no-ip.org (Postfix, from userid 1000) id 2FECB32A0F; Wed, 9 May 2007 13:01:45 -0400 (CLT) Date: Wed, 9 May 2007 13:01:45 -0400 From: Alvaro Herrera To: Jignesh Shah Cc: =?utf-8?B?5p2O5b2m?= Ian Li , PostgreSQL Performance Subject: Re: ZFS and Postgresql - WASRe: Best OS for Postgres 8.2 Message-ID: <20070509170145.GS4504@alvh.no-ip.org> References: <1178574927.533849.90730@e51g2000hsg.googlegroups.com> <463FFF76.5070108@gmail.com> <4641F672.6090508@sun.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <4641F672.6090508@sun.com> User-Agent: Mutt/1.5.13 (2006-08-11) X-Virus-Scanned: ClamAV version 0.88.5, clamav-milter version 0.88.5 on projects.commandprompt.com X-Virus-Status: Clean X-Greylist: Sender succeded SMTP AUTH authentication, not delayed by milter-greylist-1.6 (lists.commandprompt.com [192.168.2.159]); Wed, 09 May 2007 10:01:50 -0700 (PDT) X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200705/201 X-Sequence-Number: 24591 Jignesh Shah escribió: > Now comes the thing that I am still exploring > * Do we do checksum in WAL ? I guess we do .. Which means that we are > now doing double checksumming on the data. One in ZFS and one in > postgresql. ZFS does allow checksumming to be turned off (but on new > blocks allocated). But of course the philosophy is where should it be > done (ZFS or PostgreSQL). Checksums on WAL are not optional in Postgres, because AFAIR they are used to determine when it should stop recovering. -- Alvaro Herrera http://www.CommandPrompt.com/ PostgreSQL Replication, Consulting, Custom Development, 24x7 support