To drop Logfile group
alter database drop logfile group 1;
alter database drop logfile group 4;
To add Logfile on RAC
ALTER DATABASE ADD LOGFILE THREAD 1
GROUP 6 ('+DATA_SCUKOFE_SVC',
'+FRA_SCUKOFE_SVC') size 50M;
ALTER DATABASE ADD LOGFILE THREAD 2
GROUP 8 ('+DATA_SCUKOFE_SVC',
'+FRA_SCUKOFE_SVC') size 50M;
