To: Dan Gorman <dgorman@hi5.com>
cc: pgsql-performance@postgresql.org
Subject: Re: PITR Backups 
In-reply-to: <7E0807EE-B970-4869-A248-B838E42AD9EE@hi5.com> 
References: <7E0807EE-B970-4869-A248-B838E42AD9EE@hi5.com>
Comments: In-reply-to Dan Gorman <dgorman@hi5.com>
	message dated "Thu, 21 Jun 2007 16:31:32 -0700"
Date: Thu, 21 Jun 2007 20:26:45 -0400
Message-ID: <9761.1182472005@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

Dan Gorman <dgorman@hi5.com> writes:
>    All of our databases are on NetApp storage and I have been looking  
> at SnapMirror (PITR RO copy ) and FlexClone (near instant RW volume  
> replica) for backing up our databases. The problem is because there  
> is no write-suspend or even a 'hot backup mode' for postgres it's  
> very plausible that the database has data in RAM that hasn't been  
> written and will corrupt the data.

I think you need to read the fine manual a bit more closely:
http://www.postgresql.org/docs/8.2/static/backup-file.html
If the NetApp does provide an instantaneous-snapshot operation then
it will work fine; you just have to be sure the snap covers both
data and WAL files.

Alternatively, you can use a PITR base backup as suggested here:
http://www.postgresql.org/docs/8.2/static/continuous-archiving.html

In either case, the key point is that you need both the data files
and matching WAL files.

			regards, tom lane