Received: from localhost (unknown [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id C87BC6502B0 for ; Sat, 16 Aug 2008 01:56:15 -0300 (ADT) Received: from postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 74562-01 for ; Sat, 16 Aug 2008 01:56:03 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from westnet.com (westnet.com [216.187.52.2]) by postgresql.org (Postfix) with ESMTP id 8260C6503AF for ; Sat, 16 Aug 2008 01:53:30 -0300 (ADT) Received: from westnet.com (localhost [127.0.0.1]) by westnet.com (8.14.0/8.14.0) with ESMTP id m7G4rL4J006688; Sat, 16 Aug 2008 00:53:21 -0400 (EDT) Received: from localhost (gsmith@localhost) by westnet.com (8.14.0/8.13.2/Submit) with ESMTP id m7G4rK1k006684; Sat, 16 Aug 2008 00:53:20 -0400 (EDT) X-Authentication-Warning: westnet.com: gsmith owned process doing -bs Date: Sat, 16 Aug 2008 00:53:20 -0400 (EDT) From: Greg Smith X-X-Sender: gsmith@westnet.com To: Bruce Momjian cc: Mark Wong , pgsql-performance@postgresql.org Subject: Re: file system and raid performance In-Reply-To: <200808151922.m7FJMxJ21964@momjian.us> Message-ID: References: <200808151922.m7FJMxJ21964@momjian.us> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0 tagged_above=0 required=5 tests=none X-Spam-Level: X-Archive-Number: 200808/174 X-Sequence-Number: 31055 On Fri, 15 Aug 2008, Bruce Momjian wrote: > 'data=writeback' is the recommended mount method for that file system, > though I see that is not mentioned in our official documentation. While writeback has good performance characteristics, I don't know that I'd go so far as to support making that an official recommendation. The integrity guarantees of that journaling mode are pretty weak. Sure the database itself should be fine; it's got the WAL as a backup if the filesytem loses some recently written bits. But I'd hate to see somebody switch to that mount option on this project's recommendation only to find some other files got corrupted on a power loss because of writeback's limited journalling. ext3 has plenty of problem already without picking its least safe mode, and recommending writeback would need a carefully written warning to that effect. -- * Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD