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13 Posts
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Oracle RMAN (from Solaris) poor de-dupe results
Hi all
Anyone got some experience of poor dedupe ratios when backing up via Avamar initiated RMAN backups.
I am currently testing and backing up a 'static' test database once per day on a schedule. Every day I get a result of 95% changed bytes even though I know that the data in the DB has not changed.
The data is picking up Avamar retention policies and its doing a 'full backup' with 'enchanced de-dup'
Any ideas?
Thanks
Lucky85
173 Posts
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September 17th, 2012 07:00
Try to do manual RMAN backup with parameter filesperset set to 1.
Regards
Lukas
Lucky85
173 Posts
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September 18th, 2012 00:00
It is RMAN parameter, problem is that Avamar generates RMAN script automatically so you can’t edit it as far as I know… So as I wrote, you have to test it running RMAN manual backup.
Regards
Lukas
paulmaddocks_37
13 Posts
0
September 18th, 2012 00:00
Hi
Excuse my ignorance, but is that a specifc RMAN parameter or a Avamar paramter?
Happy to try it but I need to find a way of scheduling within Avamar and acheiving the dedupe ratios...
Won't be able to test it for a couple of days as my Oracle guru is away but will come back with the results later in the week.
Thanks for the assistance so far...
inkjet2000
5 Posts
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December 27th, 2012 14:00
Hey Paul,
We're seeing something similar. I've noticed with a couple of our databases that when we use our own RMAN scripts where MAXOPENFILES is set to 1 as well as FILESPERSET is set to 1, the dedupe rate appears to be a bit better. Several of our databases are seeing 35-40% new bytes on very busy databases, and 25-35% on very low use database with the canned RMAN scripts. The other disadvatage to the custom scripts we have is total loss of customization in regard to the advanced retention policies.
Let me know what your numbers look like, and what which approach your team seems to have taken.
Regards,
Justin
paulmaddocks_37
13 Posts
0
December 28th, 2012 00:00
Hi
My Oracle expert is away at the moment on leave, I will forward your message to him to look into the options you mentioned below.
We have overcome the issues with setting up some advanced retention style scripts which I will try confirm I can share on the forum.
Thanks,