X-Original-To: pgsql-performance-postgresql.org@postgresql.org Received: from localhost (mx1.hub.org [200.46.208.251]) by postgresql.org (Postfix) with ESMTP id EEA119FA4A8 for ; Thu, 15 Jun 2006 00:34:07 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.208.251]) (amavisd-new, port 10024) with ESMTP id 33794-05 for ; Thu, 15 Jun 2006 00:34:04 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey- Received: from stark.xeocode.com (stark.xeocode.com [216.58.44.227]) by postgresql.org (Postfix) with ESMTP id 1F2889FA10A for ; Thu, 15 Jun 2006 00:34:03 -0300 (ADT) Received: from localhost ([127.0.0.1] helo=stark.xeocode.com) by stark.xeocode.com with smtp (Exim 3.36 #1 (Debian)) id 1FqicE-0004ui-00; Wed, 14 Jun 2006 23:33:54 -0400 To: Mark Lewis Cc: Dan Gorman , pgsql-performance@postgresql.org Subject: Re: Postgres fsync off (not needed) with NetApp References: <9A377C54-361D-4F01-BF7A-7632FBA3453C@hi5.com> <1150322085.31200.39.camel@archimedes> In-Reply-To: <1150322085.31200.39.camel@archimedes> From: Greg Stark Organization: The Emacs Conspiracy; member since 1992 Date: 14 Jun 2006 23:33:53 -0400 Message-ID: <873be7ay8u.fsf@stark.xeocode.com> Lines: 18 User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.4 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200606/284 X-Sequence-Number: 19641 Mark Lewis writes: > On Wed, 2006-06-14 at 14:48 -0700, Dan Gorman wrote: > > > > However, if I have it attached to a NetApp that ensures data writes > > to via the NVRAM can I safely turn fsync off to gain additional > > performance? > > No. You need fsync on in order to force the data to get TO the NetApp > at the right time. With fsync off, the data gets cached in the > operating system. In fact the benefit of the NVRAM is precisely that it makes sure you *don't* have any reason to turn fsync off. It should make the fsync essentially free. -- greg