Re: What is the purpose of DBMS_RESOURCE_MANAGER.CALIBRATE_IO?
From: Grzegorz Goryszewski <grzegorzof_at_interia.pl>
Date: Mon, 21 Nov 2011 16:53:08 +0100
Message-ID: <4ECA73E4.9000603_at_interia.pl>
On 2011-11-21 14:20, Johnson, William L (TEIS) wrote:
> We have an open service request with SAP where we are working on an Oracle performance issue related to Oracle 11.2.0.1 and securefiles.
> SAP is asking us to run the calibrate_io process. Does this have any purpose internal to the database other than showing information about io stats? Does it affect the optimizer based on io response?
Hi,
please check:
*Automatic Degree of Parallelism in 11.2.0.2 [ID 1269321.1] ...*
Date: Mon, 21 Nov 2011 16:53:08 +0100
Message-ID: <4ECA73E4.9000603_at_interia.pl>
On 2011-11-21 14:20, Johnson, William L (TEIS) wrote:
> We have an open service request with SAP where we are working on an Oracle performance issue related to Oracle 11.2.0.1 and securefiles.
> SAP is asking us to run the calibrate_io process. Does this have any purpose internal to the database other than showing information about io stats? Does it affect the optimizer based on io response?
Hi,
please check:
*Automatic Degree of Parallelism in 11.2.0.2 [ID 1269321.1] ...*
When |PARALLEL_DEGREE_POLICY| is set to |AUTO|, Oracle Database determines whether a statement should run in parallel based on the cost of the operations in the execution plan and the hardware characteristics.
The hardware characteristics include I/O calibration statistics so these statistics must be gathered otherwise Oracle Database does not use the automatic degree parallelism feature.
*
and be aware of:
**Bug 10180307 - Dbrm dbms_resouce_manager.calibrate_io reports very
high values for max_pmbps [ID 10180307.8]
Regards
GregG
*
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