RE: Io calibration on Exadata
- From: "Mark W. Farnham" <mwf@xxxxxxxx>
- To: <gogala.mladen@xxxxxxxxx>, <dedba@xxxxxxxxxx>
- Date: Sat, 15 Jul 2017 19:18:23 -0400
That's one of the best public service announcements I've seen in a long
while. Very nice, Mladen.
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Mladen Gogala
Sent: Thursday, July 13, 2017 12:14 AM
Subject: Re: Io calibration on Exadata
On Thu, 13 Jul 2017 12:20:56 +1000
I've migrated a datawarehouse to my new exa and now ran io_calibrate on
it. To my horror it returns worse figures than i expect, eg 500mb per second
throughput. The old & tired ODA clocks in at 3 times that, and more.. We do
see good performance on real queries, so the calibration is cearly wrong..
Any one has any pointers? Should I use auto-dop at all on an exadata?
That depends on the release of your database. In Oracle 12.2, I would say
yes, without a hesitation. In Oracle 11G, the answer would probably be no. A
good article on CALIBRATE_IO can be found here:
Other than that, I wouldn't necessarily trust CALIBRATE_IO unconditionally.
Testing your IO is a complex task which requires a bit of planning. I would
also run Orion and SLOB to verify that the number produced by CALIBRATE_IO
are accurate. Here is another must-read article about CALIBRATE_IO:
And finally, I have to point you to the Mauro Pagano's wonderful explanation
If the results seem wrong, feel free to correct them by updating the table
SYS.RESOURCE_IO_CALIBRATE$. Long story short, I've heard horror stories
about CALIBRATE_IO in 11G and I've heard satisfied comments in 12c. Not
being a DBA, I don't have any relevant experience of my own.
Tel: (347) 321-1217
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