RMAN compression - is this reasonable?

  • From: "Schauss, Peter (ESS)" <peter.schauss@xxxxxxx>
  • To: "oracle-l@xxxxxxxxxxxxx" <oracle-l@xxxxxxxxxxxxx>
  • Date: Thu, 18 Jul 2013 19:24:46 +0000

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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