RAC to Single Instance conversion...

Had this requirement recently to convert a RAC to Single Instance DB and here's process that worked for me...btw..this is a 10.2.x cluster.

• backup the db's
• shutdown the cluster db's using 'srvctl stop database '
• check the status of nodeapps using 'srvctl status nodeapps -n '
• stop the nodeapps on all the nodes 'srvctl stop nodeapps -n '...repeat this for all the nodes
• stop the cluster CRS services as root..'/etc/init.d/init.crs stop'
• gather the patches installed using 'opatch lsinventory'
• shutdown the nodes ...and restart the node that will be used for single instance db's.
• present the storage to this single node as ext3 filesystems
• verify all the filesystems are present ....
• rename the oracle_home directory ...say db_1 as db_1.RAC (if you need to drop the home for space reasons, make sure you backup the tns file for ref.)
• reinstall the single instance binaries
• apply all the interim patches (using the info collected above using lsinventory)
• remove all the cluster related settings from the old init.ora
• change the cluster_database=false and cluster_database_instances=1
• startup the instance using the modified pfile
• disable thread 2 using 'alter database disable thread 2'
• drop the log groups belonging to thread 2...and 3...etc (you may need to switch the logs if the archived=NO
• drop the thread 2 undo tablespace
• run a 'show parameter cluster' to verify there're no references to instance 2
• shutdown immediate
• create spfile from pfile;
• startup
• create the listener
• update the tnsnames.ora as required
• update the oracle autostart scripts as required