Dataguard Switch Over Steps In Case of Disaster 1. Cancel the Archivelog Apply: alter database recover managed standby database cancel; 2. Check whether any gap exists between archivelogs: SELECT THREAD#, LOW_SEQUENCE#, HIGH_SEQUENCE# FROM V$ARCHIVE_GAP; 3. If gap exists OS copy the archive files to standby and then issue this command. In my case I had 4 archivelogs not reaching to standby. ALTER DATABASE REGISTER PHYSICAL LOGFILE '/RECOVERY_DESTINATION/STAN/archivelog/2012_02_07/o1_mf_1_15_7m1w964b_.arc'; ALTER DATABASE REGISTER PHYSICAL LOGFILE ‘/RECOVERY_DESTINATION/STAN/archivelog/2012_02_07/o1_mf_1_16_7m1wdr56_.arc’; ALTER DATABASE REGISTER PHYSICAL LOGFILE '/RECOVERY_DESTINATION/STAN/archivelog/2012_02_07/o1_mf_1_17_7m1wg7wp_.arc’; ALTER DATABASE REGISTER PHYSICAL LOGFILE '/RECOVERY_DESTINATION/STAN/archivelog/2012_02_07/o1_mf_1_18_7m1wrrmz_.arc’; 4. ALTER DATABASE RECOVER MANAGED STANDBY DATABASE FINISH FOR...