RMAN Backups in RAC

All backups by default go to FRA disk group in RAC. Take RMAN backup to custom location in Oracle RAC

RMAN> backup as compressed backupset database format '+RMANDG';

or

run{
allocate channel ch1 format '+RMANDG/RAC_DB_Backup_%u';
allocate channel ch2 format '+RMANDG/RAC_DB_Backup_%u';
backup database plus archivelog;
release channle ch1;
release channel ch2;
}