A quick word of warning about database PSU 11.2.0.2.2

I am playing around with the Grid Infrastructure 11.2.0.2 PSU 2 and found an interesting note on My Oracle Support regarding the Patch Set Update. This reminds me that it’s always a good idea to search for a patch number on Metalink before applying a PSU. It also seems to be a good idea to wait for a few days before trying a PSU (or maybe CPU) on your DEV environment for the first time (and don’t even think about applying a PSU on production without thorough testing!)

OK, back to the story: there is a known issue with the patchset which has to do with the change in the Mutex behaviour which the PSU was intended to fix. To quote MOS note “Oracle Database Patch Set Update 11.2.0.2.2 Known Issues (Doc ID 1291879.1)”, Patch 12431716 Is a Recommended Patch for 11.2.0.2.2. In fact, Oracle strongly recommends you to apply the patch to fix Bug 12431716 – Unexpected change in mutex wait behavior in 11.2.0.2.2 PSU (higher CPU possible).

In a nutshell, not applying the patch can cause your system to suffer from excessive CPU usage and more than expected mutex contention. More information can be found in the description of Bug 12431716  Mutex waits may cause higher CPU usage in 11.2.0.2.2 PSU / GI PSU which is worth reading.

Besides this, the PSU was applied without any problems to my four node cluster, I just wish there was a way to roll out a new version of opatch to all cluster node’s $GRID_HOME and $ORACLE_HOME in one command. The overall process for the PSU is the same as already described in my previous post about Bundle Patch 3:

1. Get the latest version of OPatch
2. Deploy OPatch to $GRID_HOME and $ORACLE_HOME (ensure permissions are set correctly for the OPatch in $GRID_HOME!)
3. Unzip the PSU (Bug 11724916 – 11.2.0.2.2 Patch Set Update (PSU) (Doc ID 11724916.8)), for example to /tmp/PSU
4. Change directory to where you unzipped (/tmp/PSU) and become root
5. Ensure that $GRID_HOME/OPatch is part of the path
6. Read the readme
7. Create an OCM response file and save it to say, /tmp/ocm.rsp
8. Start the patch as root: opatch auto and supply the full path to the OCM response file (/tmp/ocm.rsp)
9. Apply the beforementioned one-off patch

Then wait, and after a little while you spend trailing the logfile in $GRID_HOME/cfgtoollogs/ and having a coffee the process eventually finishes. Repeat on each node and you’re done. I’m really happy there aren’t these long readme files anymore with 8 steps to be performed, partially as root, partially as CRS owner/RDBMS owner. It reduces tge tune ut takes to apply a PSU significantly.

Happy patching!