Are you using HugePages or AMM?
Are you seeing ORA-27123 in the alert log?
What is the size of your SGA?
That might be where you start.
Here is a link that might help:
On Thu, Apr 13, 2017 at 1:39 PM, Sandra Becker <sbecker6925@xxxxxxxxx>
Oracle 126.96.36.199, 2-node RAC
We recently upgraded to 188.8.131.52 and began experiencing some performance
issues. We have addressed most of them. While reviewing the GRID
alert.log, I noticed errors on shmmax. the setting is different on the two
nodes. Node B has a setting twice as high as node A. Node A has a setting
above the minimum required, so we're good on that score. I've been
searching MOS and googling, but haven't found anything to address this
specific situation yet.
Questions: Is this really hurting us? Could it be causing some
performance degradation? We plan to set them the same, but is it something
we need to do sooner rather than later?
Thank you in advance for any guidance you can provide.