Received: from localhost (unknown [200.46.204.184]) by postgresql.org (Postfix) with ESMTP id B8B762E30B3 for ; Thu, 31 Jan 2008 11:05:02 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.184]) (amavisd-maia, port 10024) with ESMTP id 11502-02 for ; Thu, 31 Jan 2008 11:04:45 -0400 (AST) Received: from smtp162.iad.emailsrvr.com (smtp162.iad.emailsrvr.com [207.97.245.162]) by postgresql.org (Postfix) with ESMTP id B8AD82E02D5 for ; Thu, 31 Jan 2008 11:02:09 -0400 (AST) Received: from relay6.relay.iad.emailsrvr.com (localhost [127.0.0.1]) by relay6.relay.iad.emailsrvr.com (SMTP Server) with ESMTP id B7B506FD6B0; Thu, 31 Jan 2008 10:02:07 -0500 (EST) Received: by relay6.relay.iad.emailsrvr.com (Authenticated sender: chander-AT-otg-nc.com) with ESMTP id 3A6A26FD8A6; Thu, 31 Jan 2008 10:02:07 -0500 (EST) Message-ID: <47A1E2F6.7060108@otg-nc.com> Date: Thu, 31 Jan 2008 10:02:14 -0500 From: Chander Ganesan User-Agent: Thunderbird 2.0.0.9 (Windows/20071031) MIME-Version: 1.0 To: Magnus Hagander CC: Simon Riggs , Phillip Smith , 'Dominic Carlucci' , pgsql-general@postgresql.org, pgsql-admin@postgresql.org, carlucci@cae.ca Subject: Re: [GENERAL] Backup References: <00a201c85ee9$fbd1ca00$9b0014ac@wbaus090> <1201252875.4257.387.camel@ebony.site> <47A1BD51.3030902@otg-nc.com> <1201786128.4453.287.camel@ebony.site> <20080131143405.GC21660@svana.org> <20080131144314.GH11977@svr2.hagander.net> In-Reply-To: <20080131144314.GH11977@svr2.hagander.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200801/295 X-Sequence-Number: 28069 Magnus Hagander wrote: > On Thu, Jan 31, 2008 at 03:34:05PM +0100, Martijn van Oosterhout wrote: > >> On Thu, Jan 31, 2008 at 01:28:48PM +0000, Simon Riggs wrote: >> >>> That sentence has no place in any discussion about "backup" because the >>> risk is not just a few transactions, it is a corrupt and inconsistent >>> database from which both old and new data would be inaccessible. >>> >> Hmm? I thought the whole point of a filesystem snapshot was that it's >> the same as if the system crashed. And I was fairly sure we could >> recover from that... >> > > That was my assumption as well. *Assuming* that the filesystem snapshot is > consistent. There are a bunch of solutions that don't do consistent > snapshots between different partitions, so if your WAL or one tablespace is > on a different partition, you'll get corruption anyway... (seen this in > Big Commercial Database, so that's not a pg problem) > Agreed. That's why I made it a point to mention that all of your tablespaces should be on the same file system... In hindsight, I should have also stated that your WAL logs should be on the same file system as well... -- Chander Ganesan Open Technology Group, Inc. One Copley Parkway, Suite 210 Morrisville, NC 27560 919-463-0999/877-258-8987 http://www.otg-nc.com