I have a full RMAN backup of 2-node 11gR2 database. Data files are on ASM. I lost some datafiles so what is the procedure of restoring from RMAN backup on the same ASM. Do I have to restore/recover from one instance without making cluster_database=false. Please provide all the steps. Thank you in advance.
The RESTORE and RECOVER process is the same as with non-RAC , non-ASM environments.
Nevertheless, the RAC documentation has a separate chapter on this : http://docs.oracle.com/cd/E11882_01/rac.112/e41960/backup.htm#i443637
Since you've lost only some datafiles, we presume that the controlfile and system and undo datafiles are still present -- meaning that the database might be OPEN. (if system or undo datafiles are lost, the database cannot be in an OPEN state but must be in a MOUNT state).
You simply RESTORE DATAFILE n for each datafile and then RECOVER DATABASE. The Recovery would be COMPLETE Recovery as you have the online redo logs still present. The node where you do the RECOVER from must have access to the ArchiveLogs of both the nodes in the cluster.
Hemant K Chitale