Convert an Oracle 10g RAC database to single instance

Question

In an attempt to reduce the complexity of a solution, I've been asked to convert a two node Oracle 10g RAC production database to single instance. The database is running on RHEL5 with ASM on SAN.

I imagine at least the following steps will be required:

• Remove the instances from cluster ready services
• Restrict the second node's access to shared storage
• Remove redo logs for second instance
• Drop undo tablespace for second instance
• Remove references to second instance from the pfile/spfile
• Relink the Oracle binaries, refer to post from Gaius

Any other considerations? Might it be better to create a single node physical standby?

Does anyone know of a related whitepaper or metalink note?

Answer 1

Does this link helps?

For ASM, edit the ASM pfile and remove these lines

cluster_database=TRUE
+ASM.instance_number=<somthing> 

You may also found metalink 239998.1 helpful if rootdelete.sh fails.

Answer 2

You will also need to relink the Oracle binaries:

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

Of course, if you create a single-node standby it will already be "un-RAC'd" but you will still need to "clean up" the second redo thread etc. Just had a quick look on Metalink and their search engine finds lots of results converting from single instance to RAC but I don't think Oracle wants you to do it the other way 'round...