Use of the LIMIT parameter in Exadata IORM plan artificially throttles LGWR I/O
(Doc ID 1562397.1)
Last updated on FEBRUARY 21, 2019
Applies to:Oracle Exadata Storage Server Software - Version 220.127.116.11.1 to 18.104.22.168.1 [Release 11.2]
Information in this document applies to any platform.
Incorrect over-throttling of LGWR I/O operations can be seen in Exadata with image version before 22.214.171.124.0, 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))
The issue may be observed after implementing or modifying an IORM plan in Exadata.
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