Changing Capacity On-Demand Core Count in Exadata
We recently implemented an Exadata X6 at a one of client sites (yes, we don’t Oracle ACS, we do it ourselves). However, the client failed to tell us that they had licensed only a subset of the cores per compute, after we actually had implmeneted and *migrated* production databases onto the X6. So how do we set the core count correctly after implementation (post-OEDA run). We heard horror stories about other folks saying they needed to re-image to set core count. To be specific, its easy to increase cores, but decrease is nasty business.
The steps below are ones we used to decrease the core count:
1. Gracefully stop all databases running on all compute nodes.
2. Login to the compute nodes as root and run the “dbmcli” utility
3. Display the current core count using the following command:
LIST DBSERVER attributes coreCount
4. Change the core count to the desired count using this command (this needs done on all compute nodes):
ALTER DBSERVER pendingCoreCount = 14
NOTE: Since we are decreasing the number of cores after installation of the system, the FORCE option needs to be done.
ALTER DBSERVER pendingCoreCount = 14 FORCE
6. Verify the change was correct by using the “LIST” command in step 3.
Just FYI… Troubleshooting
If there is an issue with the MS service starting up, it could be because of the Java being used on the system.
For Exadata release 126.96.36.199.1.160411, the version of Java was 188.8.131.52 and was flagged by a security audit as a vulnerability and was removed from the system. When the system rebooted, the MS service couldn’t start back up because Java was removed. Follow these steps to reinstall Java and get the MS service restarted on the compute nodes.
1. Download the latest JDK from the Oracle site. NOTE: The RPM download was used.
2. Install the JDK package on the system:
rpm -ivh jdk-8u102- linux-x64.rpm
3. Redeploy the MS service application:
/opt/oracle/dbserver/dbms/deploy/scripts/unix/setup_dynamicDeploy DB -D
4. Restart the MS service:
ALTER DBSERVER RESTART SERVICES MS