Oracle DBA Warriors Blog

Guarantee Restore Point Primary-Standby Environment: When we have a Data Guard environment (Primary RAC and Standby Standalone Databases) and we want to make use of restore points. We need to follow below steps. Always create a restore point on the standby database first then in Primary. The main reason for this is because the SCN of the standby must be less than the SCN of the primary in case you need to flashback your database. If we didn’t follow the step 1 then we need to rebuild the standby. 1.) Stop Managed Recovery on the Standby Database using SQL*PLUS or Data Guard Broker. $ dgmgrl sys/<Password>@<PRIM/STDBY> DGMGRL>  show database ' STDBY '; edit database 'STDBY' set state = 'APPLY-OFF'; show database ' STDBY ';   OR STDBY.SYS.SQL> select inst_id, process, status, thread#, sequence#, block#, blocks from gv$managed_standby order by inst_id; alter database recover managed standby database ca...

Oracle Background Processes - System Monitor (SMON) :  SMON stands for system monitor process is the most critical background process for Oracle Database. It performs critical tasks such as instance recovery,dead transaction recovery and maintenance tasks such as temporary space reclamation, data dictionary cleanup, and undo tablespace management. It is a mandatory background process for running an Oracle instance. It is the heart of oracle architecture.It performs all system monitoring functions on the oracle database, SMON checks regularly to see whether it is needed. Other processes can call SMON if they detect a need for it. It checks the space of SYSTEM tablepace and if it is running short of it displays an error message. SMON wakes up periodicaly to perform housekeeping activities like cleanup of temporary segments that are no longer needed.  It also coalesces contiguous free extents in dictionary managed tablespaces that have PCTINCREASE set to a non-zero valu...

Flashback Database to Restore Point in Primary-Standby Environment: When we have a Data Guard environment (Primary RAC and Standby Standalone Databases) and we want Flashback database to restore point. We need to follow below steps. a) Always flashback the primary database first. Then follow below step for Standby. b) On the primary, connect using RMAN and list the incarnations. c) On the standby, cancel the recovery and flashback the standby to restore point created earlier. d) On the standby, connect using RMAN and list the incarnations. e) If there is a mismatch in incarnation between primary and standby then need to reset the incarnation of standby and start recovery (Details not available in this DOC). 1)    Disable Log Transport Services to the Standby Database for the Destination serving the Standby Database on all Primary Instances: $ dgmgrl sys/<Password>@<PRIM/STDBY> DGMGRL>  show database 'PRIM '; edit database...