Re: RMAN Compression experiences

You are spot on about additional CPU costs, but frankly it does not seem to be onerous from what I've seen. The overall reduction in IO often is more than worth the additional CPU costs.

RF  

Robert G. Freeman
Author:
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 Feature
Blog: http://robertgfreeman.blogspot.com (Oracle Press)

• Original Message ---- From: Jared Still <jkstill_at_gmail.com> To: Brandon.Allen_at_oneneck.com Cc: j.miranda_at_sermatica.es; oracle-l_at_freelists.org Sent: Tuesday, January 15, 2008 1:39:56 PM Subject: Re: RMAN Compression experiences

Take a look at the CPU utilization levels before and during the backup.

If your CPU usage is fairly low, then the backups may go faster than before.

If the CPU usage is already fairly high (such as a 24x7 database) then backup

could very well take longer, and response time of the users could suffer quite a bit.

There are cases too where you might want to reduce the number of channels if doing compressed backups.

If the database is being backed up directly to tape, adding compression to

the mix may slow down data sent to tape so much that the tape stops streaming.

Stopping and starting tapes in the middle of a backup is something you usually want to avoid.

Jared

On Jan 15, 2008 10:03 AM, Allen, Brandon <Brandon.Allen_at_oneneck.com> wrote:

My only negative experience with it so far was that the restores took twice as long. This timing was pretty consistent through testing it about 5 times. This was with Oracle 10.2.0.2, AIX 5.3 and Netbackup 6.0. My backups were consistently faster and much smaller so that's great, but with the restores taking twice as long we decided it wasn't acceptable for our production database, but it's great for test & dev.  

Regards,

Brandon

Privileged/Confidential Information may be contained in this message or attachments hereto. Please advise immediately if you or your employer do not consent to Internet email for messages of this kind. Opinions, conclusions and other information in this message that do not relate to the official business of this company shall be understood as neither given nor endorsed by it.

--

Jared Still
Certifiable Oracle DBA and Part Time Perl Evangelist

--

http://www.freelists.org/webpage/oracle-l Received on Tue Jan 15 2008 - 16:08:12 CST