RE: RMAN compression - is this reasonable?

From: Joel Slowik <jslowik_at_cps92.com>
Date: Thu, 18 Jul 2013 19:30:29 +0000
Message-ID: <3942346a8b7147828500ac521b0171af_at_BLUPR07MB051.namprd07.prod.outlook.com>



Hi Peter,

I have found a 10 to 1 ratio on a couple relatively smaller systems that I manage. I use the default compression algorithm on most of our environments and I've grown accustom to expect close to that ratio since most of our environments tend to store very similar data.

-joel

-----Original Message-----

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Schauss, Peter (ESS) Sent: Thursday, July 18, 2013 3:25 PM
To: oracle-l_at_freelists.org
Subject: RMAN compression - is this reasonable?

This is Oracle 11.2.0.3 running on Windows Server 2003. I am in the process of setting up RMAN backups. The relevant part of my backup script says:

"backup as compressed backupset database plus archivelog;"

EM says that the database is about 150 gb which seems to correspond roughly to the sum of the data file sizes. To get an idea of approximately how much of that space is used I ran:

select sum(bytes)/1000000000 from dba_segments;

and got about 63 gb. This is a development database so I would not expect a large amount of data in the archive logs.

The sum of the backup file sizes is just under 10 gb.

Based on this, it looks like I am getting a compression ratio of about 6 to 1. Is this typical for the default compression algorithm?

Thanks,
Peter Schauss
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http://www.freelists.org/webpage/oracle-l Received on Thu Jul 18 2013 - 21:30:29 CEST

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