Re: compressed backup - is this a reasonable size

From: Tony van Lingen <>
Date: Thu, 23 Apr 2009 11:16:14 +1000
Message-ID: <>

That is interesting. I was just discussing this with my collegue who specialises in RMAN backups. He asserts exactly the opposite where it comes to backup times. As an example, we have an GIS database of about 1TB (10g) which backs up in 30 mins in standard mode. When he enables compression it takes up to 6 hours and is very cpu intensive. Apart from that, he agrees that the compression is quite good.

Apparently the compression also should not be used in combination with a compressed tape device.


Robert Freeman wrote:
> Very reasonable. Compression can do wonders for the size of backup
> sets! It can also significantly improve overall backup times. What
> were your times for the backup compressed and non-compressed and how
> much of a difference in CPU did they make.
> Be aware that someone on here mentioned a bug with compression just a
> few days ago.I looked in Metalink for compression related bugs and
> found a few. In a very quick looksee I find most the bugs seem to be
> related to backups as opposed to restores. So it seems if you can get
> a good backup, then you might well be ok. As always, test test test,
> your restores. No piece of software is perfect! :-) On a regular basis
> continue to test your restores just in case a bug creeps in. My
> personal experience with Compression has been very positive.
> Robert
> Robert G. Freeman
> Author:
> OCP: Oracle Database 11g Administrator Certified Professional Study
> Guide (Sybex)
> Oracle Database 11g New Features (Oracle Press)
> Portable DBA: Oracle (Oracle Press)
> Oracle Database 10g New Features (Oracle Press)
> Oracle9i RMAN Backup and Recovery (Oracle Press)
> Oracle9i New Features (Oracle Press)
> Other various titles out of print now...
> Blog:
> The LDS Church is looking for DBA's. You do have to be a Church member in
> good standing. A lot of kind people write me, concerned I may be breaking
> the law by saying you have to be a Church member. It's legal I
> promise! :-)
> ------------------------------------------------------------------------
> *From:* Jeffrey Beckstrom <>
> *To:* oracle-l-freelists <>; oracle-db-l
> <>
> *Sent:* Wednesday, April 22, 2009 7:36:52 AM
> *Subject:* compressed backup - is this a reasonable size
> 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.
> Jeffrey Beckstrom
> Database Administrator
> Greater Cleveland Regional Transit Authority
> 1240 W. 6th Street
> Cleveland, Ohio 44113

Received on Wed Apr 22 2009 - 20:16:14 CDT

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