Unknown Exadata Cell Parameter - "_cell_fc_toresilver_limit_chdrs"
Date: Thu, 14 Dec 2023 23:21:46 +0300
Message-ID: <CAOW9pnSRuaP=wLJ1m5MUZ6Zp2s9LqK6TnxPdY05mBfqK12AukQ_at_mail.gmail.com>
Hi all Oracle enthusiasts,
Do you have any information about the "_cell_fc_toresilver_limit_chdrs"
parameter?
It is set on my environment (X7-2) cellinit.ora. It is an undocumented and
non-default configuration.
I could not find any information about it, but it is commented as "It is set to reduce Internal IO on exadata cells". We do not have prior knowledge about it.
Also I have screenshots of *AWR reports - Exadata Statistics - Top IO
Reasons by MB * section.
(Before and after parameter change)
Before _cell_fc_toresilver_limit_chdrs parameter is set: https://drive.google.com/file/d/1PEcjUYAuG8SNTq1vfXLl0fyoeoffSLhq/view?usp=drive_link
After "_cell_fc_toresilver_limit_chdrs"=6000000 https://drive.google.com/file/d/12tDsDvt22oFyEaQtRdMsXcCYduw9992A/view?usp=drive_link
According to the screenshots, It reduces Internal IO done by storage servers dramatically, but there may be a trade-off which i do not know.
I want to clear this parameter as it is a non-default configuration. It was set on image version 20.1.5.0.0.201209 and it has been retained for years.
Exadata image version is 22.1.17 now.
If anybody can share more information about what this parameter does, I
will be glad.
Regards,
Osman DİNÇ.
--http://www.freelists.org/webpage/oracle-l Received on Thu Dec 14 2023 - 21:21:46 CET