Oracle Kernel RAC: ON and OFF

Oracle Kernel needs to switch with ORACLE RAC ON / OFF when you convert from Standalone to RAC or vice versa.

In some cases, you may want to enable or disable the RAC options for testing purposes –

Disabling and enabling RAC options are available only for UNIX/LINUX platforms.

I haven’t checked on Windows RAC Instances.

Use the following steps to disable RAC (known as RAC OFF):

1.         Log in as the Oracle software owner in my case (oracle) (which is typically the UNIX account oracle) in all nodes.

2.         Shutdown normally all the instances on each and every node.

3.     Go to $ORACLE_HOME/rdbms/lib:
$ cd $ORACLE_HOME/rdbms/lib

4.         Execute below make command to relink the Oracle binaries without the RAC option:

make -f ins_rdbms.mk rac_off

rebuild oracle

This normally runs for few minutes and should not pose any errors.
(if any error fixed it or immediate contact with oracle support)

5.         Now relink the Oracle binaries:

cd $ORACLE_HOME/bin
#make -f ins_rdbms.mk oracle

relink oracle

6.         Now the Oracle binaries are relinked with the RAC OFF option.
You may have to edit the parameter file init.ora or SPFILE parameters accordingly (Cluster_Database, Undo, Threads) etc.

Use the following steps to enable RAC (known as RAC ON):

1.                   Log in as the Oracle software owner in my case (oracle) (which is typically the UNIX account oracle) in all nodes.

2.                   Shutdown normally all the instances on each and every node.

3.               Go to $ORACLE_HOME/rdbms/lib:
$ cd $ORACLE_HOME/rdbms/lib

4.                   Execute the following make command to relink the Oracle binaries without the RAC option:

make -f ins_rdbms.mk rac_on

rebuild oracle

This normally runs for a few minutes and should not pose any errors.
(Get in touch with Oracle Support in case of any error)

5.                   Now relink the Oracle binaries:

cd $ORACLE_HOME/bin

#make -f ins_rdbms.mk oracle

relink oracle

Now the Oracle binaries are relinked with the RAC ON option. You may need to edit the parameter file init.ora or SPFILE parameters accordingly like (Cluster_Database,Undo,Threads…etc).

Manual make commands

While the Oracle relink command will automatically run the make commands, you still may run them menually:

For executables: oracle, exp, imp, sqlldr, tkprof, mig, dbv, orapwd, rman, svrmgrl, ogms and ogmsctl

cd $ORACLE_HOME/rdbms/lib
make -f ins_rdbms.mk install

For sqlplus

cd $ORACLE_HOME/sqlplus/lib
make -f ins_sqlplus.mk install

For executables: dbsnmp, oemevent, oratclsh

cd $ORACLE_HOME/network/lib
make -f ins_oemagent.mk install

For executables: names, namesctl

cd $ORACLE_HOME/network/lib
make -f ins_names.mk install

For executables: osslogin, trcasst, trcroute, onrsd, tnsping

cd $ORACLE_HOME/network/lib
make -f ins_net_client.mk install

For executables: tnslsnr, lsnrctl

cd $ORACLE_HOME/network/lib
make -f ins_net_server.mk install

For more details on using the relink command, see MOSC Note: 131321.1 titled "Using Oracle relink on UNIX".