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RE: RMAN Performance Maladies

From: Michael Fontana <>
Date: Tue, 13 Feb 2007 14:48:15 -0500
Message-ID: <>

OK - on the raid 5 issue - just to be sure everyone knows I am comparing apples to apples:  

SQLBACKTRACK was writing to the same raid5 san mount point.  

Jared hit on something that will cause me to do some more testing - and that is that whilst sqlbacktrack merely backs up the datafiles to disk (a file-based backup), rman is checking blocks, etc.  

Someone also suggested setting up RMAN to do a file-based backup. Haven't seen that documented anywhere, but if it's an option, we'd certainly consider it.  

On the issue of SLA - I agree it was set a long, long time ago when our largest databases were about 60m, and probably should be revisited, but our boss has not yet given us permission to go to incrementals until we know all of our options here.  

One thing that is not an apples to apples comparison that we need to test: We've never backed up THIS database with SqlBackTrack after migrating it to 10g 64-bit. I will let the list know how that turns out.    

[] On Behalf Of Naqi Mirza Sent: Monday, February 12, 2007 11:59 PM To: Jared Still
Subject: Re: RMAN Performance Maladies

This is true (RAID5:READS), the strange thing , though, is there is also a reporting server - which is not an entire clone of this database - but pretty close to it.
If users are asked to disconnect from the reporting server (basically no load) and a test backup is performed via rman - the throughput achieved is 50mb/s. The storage (that houses the database) is configured in the same manner, also uses RAID5. The backup is to the same tape drives. I understand the significance of a number like 666, but whats up with 50. Is it possible, though, when a large number of disks (100+) are part of a RAID5 configuration for the controllers involved to become bound with i/o requests?
Sorry , for the slight hijack of your thread Michael.

On 2/12/07, Naqi Mirza <> wrote:

        The problem I witnessed at a certain site - never got resolved, the site was also using RAID 5 - I suspected this as the culprit         

I would not expect RAID5 to be a problem during backup, unless there is a
lot of write activity to the drives during that time.

Jared Still
Certifiable Oracle DBA and Part Time Perl Evangelist


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Received on Tue Feb 13 2007 - 13:48:15 CST

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