RE: compressed backup - is this a reasonable size

  • From: <Joel.Patterson@xxxxxxxxxxx>
  • To: <riku.rasanen@xxxxxxxxxxxxxxxx>
  • Date: Thu, 23 Apr 2009 09:18:02 -0400

Be sure to keep your redundancy policy to at least one day... if you are 
deleting your input.  It takes at least one archive log to restore the 
database, so you want them copied of to tape or someplace before they 


Joel Patterson
Database Administrator
904 727-2546

-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On 
Behalf Of Riku Räsänen
Sent: Wednesday, April 22, 2009 10:11 AM
To: JBECKSTROM@xxxxxxxxx
Cc: oracle-l-freelists; oracle-db-l
Subject: Re: compressed backup - is this a reasonable size

It depends greatly.

I'd say on the average the compression is from 1:5 to 1:10, though I have
seen compression of over 1:20.

Depends on the number of empty blocks (which RMAN does not read), how much
repetition there is in the data and so on.

I'd say that from 17G to 3G is reasonable.

> Just ran the following command.  This is our first RMAN backup.  It backed
> up a 17G database into about 3G of files.  Is this reasonable?????
> backup as compressed backupset database plus archivelog delete input;
> Backup states it finished normally.

Riku Räsänen
Kantamestarit Oy



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