Oracle Database Discussions

Hello.

I have a customer who have migrated from a non-RAC to a RAC database and the same query is performing slower now. After taking care of all of the init parameters to make sure we are comparing apples to apples, we achieved the same exact explain plan in both databases. Still, it executes a lot slower in the RAC database.

I then analyzed the wait events and found the problem to stem from the RAC Global Cache (GC) buffer waits.

Here are the waits that I am seeing in the RAC database that I am not seeing in the non-RAC database:

Event waited on Times Max. Wait Total Waited
---------------------------------------- Waited ---------- ------------
gc cr block 3-way 3429 0.00 1.27
gc current block 2-way 2560 0.00 0.68
gc cr block 2-way 6947 0.00 1.93
gc cr grant 2-way 2389 0.00 0.35


How can I tune my RAC database to minimize these waits?

thanks
Boris