Whilst running the EM11g installer I received an error telling me that the value of the initi parameter cluster_database was incorrect.

As I was trying to install EM11g on a single instance database this was not expected at all.

Looking into the logfiles crated I discovered that this error was being thrown out as the installer was querying the Real Application Clusters paramter in V$option and discovering that it was true?

Now although I do have RAC Enabled in this ORACLE_HOME I am not currently hosting any RAC databases, so on this occasion I was able to relink Oracle in this ORACLE_HOME with RAC turned off.

1. shutdown all db's using this ORACLE_HOME
2. cd $ORACLE_HOME/rdbms/lib
3. make -f ins_rdbms.mk rac_off ioracle
4. restart all db's and check v$option

If I was then going to use the same ORACLE_HOME for RAC and non-RAC databases I could then enable RAC once the Em11g install completed, or create a seperate ORACLE_HOME for the EM11g Repository Database.