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configure Large Pool [message #360847]

Mon, 24 November 2008 02:26

rsreddy28
Messages: 295
Registered: May 2007

Senior Member

Hello ,

We have implemented RMAN backups on our server . And we want to configure Large Pool for our operation and we have our backups going to both disk as well as to the Tape.

What should be the formula for setting up the Large Pool .

Kindly help me out.

--Raj

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Re: configure Large Pool [message #360851 is a reply to message #360847]

Mon, 24 November 2008 02:43

Michel Cadot
Messages: 68716
Registered: March 2007
Location: Saint-Maur, France, https...

Senior Member
Account Moderator

RMAN uses buffers to work. The size of the buffers depends on the number of RMAN channels you create.

For backup on disk, the size of the RMAN buffers is:
16 MB * number_of_allocated_channels.

For backup on tape, it depends upon the size of tape buffer given by the parameter BLKSIZE (default is 256K). It is:
(16MB+4*BLKSIZE) * number_of_allocated_channels.

You have to use other areas you may use, parallel query buffers or the like, see Database Concepts.

Regards
Michel

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Re: configure Large Pool [message #360875 is a reply to message #360851]

Mon, 24 November 2008 04:06

rsreddy28
Messages: 295
Registered: May 2007

Senior Member

Hi Michel,

Thanks for the reply. But I've a small doubt with respect to Tape backups. You've specified as (16MB+4*BLKSIZE) * number_of_allocated_channels.

Why is the value 16 MB used even for the Tape backups as well as disk backups . what is the significance of 16 MB there .

--Raj

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Re: configure Large Pool [message #360877 is a reply to message #360875]

Mon, 24 November 2008 04:13

Michel Cadot
Messages: 68716
Registered: March 2007
Location: Saint-Maur, France, https...

Senior Member
Account Moderator

Internal stuff the same than for disk.

Regards
Michel

[Updated on: Mon, 24 November 2008 04:13]

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Re: configure Large Pool [message #360878 is a reply to message #360877]

Mon, 24 November 2008 04:16

rsreddy28
Messages: 295
Registered: May 2007

Senior Member

Michel,

If you dont mind can you please elaborate on that 16 MB , or if any link on that will be appreciated .

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Re: configure Large Pool [message #360888 is a reply to message #360878]

Mon, 24 November 2008 04:43

Michel Cadot
Messages: 68716
Registered: March 2007
Location: Saint-Maur, France, https...

Senior Member
Account Moderator

It was or is in the documentation, I can't remember where.
No explaination why this 16MB, just it is the figure.

Regards
Michel

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Re: configure Large Pool [message #360894 is a reply to message #360888]

Mon, 24 November 2008 04:55

rsreddy28
Messages: 295
Registered: May 2007

Senior Member

Yes, even I read in the documentation that it is 16 MB per channel , but no where it's specified why 16 MB only.

Anyway thanks and please post in this forum if you find the reason behind this 16 MB .

And after googling a lot I did find one intresting article on how to configure Large Pool and think that it will be useful to some extent

http://sysdba.wordpress.com/2007/05/08/how-to-calculate-the-minimum-size-of-large_pool_size-for-io-slaves-rman-and-memory-utilization /

Hope this helps.

--Raj

[Updated on: Mon, 24 November 2008 05:52]

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