Use of the LIMIT parameter in Exadata IORM plan artificially throttles LGWR I/O (Doc ID 1562397.1)

Last updated on FEBRUARY 06, 2014

Applies to:

Oracle Exadata Storage Server Software - Version 11.2.3.2.1 to 11.2.3.2.1 [Release 11.2]
Information in this document applies to any platform.

Symptoms

Incorrect over-throttling of LGWR I/O operations can be seen in Exadata with image version before 11.2.3.3.0, when IORM plan is in use and with the LIMIT parameter explicitly specified.

This is an example of such IORM plan:
CellCLI> alter iormplan
dbplan=((name=ORCL1, level=1, allocation=40, limit=40, flashcache=on),  -
(name=ORCL2,  level=1, allocation=40, limit=40, flashcache=on),  -
(name=ORCL3, level=1, allocation=15, flashcache=off),  -
(name=other, level=1, allocation=5, flashcache=off))


Changes

The issue may be observed after implementing or modifying an IORM plan in Exadata.

Cause

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