I have a 5.5tb database with little/no empty blocks that compresses down to 700gb, so I ouwld say 17gb to 3 is reasonable. Quest has a new product that supposedly increases the compression ratio of rman backups siginificantly, I have been meaning to try it out but haven't got the chance as of yet. Ken -----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 www.kantamestarit.fi -- //www.freelists.org/webpage/oracle-l -- //www.freelists.org/webpage/oracle-l