Oracle Data Guard 12c Feautures
SYSDG Privilege
A special privilege "SYSDG" has been introduced to simplify Dataguard operations.
Far Sync Instance
A New Standby destination type is allowed in Active Dataguard environment that ensures zero data loss failover and zero performance impact on Primary Database, is called "Far Sync Instance". This destination contains parameterfile, controlfile, and standby redo logs (SRLs), it receives the redo from Primary Database, and archives it to local destination through Standby Redo Logs. There are no Datafiles here. Technically, A Standby Database Instance without Datafiles is called Far Sync Instance. A far sync instance consumes very little disk and processing resources, yet provides the ability to failover to a terminal destination with zero data loss, as well as offload the primary database of other types of overhead (for example, redo transport).
To setup Far Sync Instance:
(Same as configuring Dataguard except backup/restore operations of the Primary Database)
1)Create pfile from spfile of the Primary, and copy to to Far Sync Server, and start the Instance
2)Add the Far Sync Destination, EX: "CDBFS"(Net Service Name/DB_UNIQUE_NAME), to Dataguard configuration (under LOG_ARCHVE_CONFIG=DG_CONFIG)
3)Set a new destination parameter to enable Log Transport Services, EX: LOG_ARCHIVE_DEST_3 & LOG_ARCHIVE_DEST_STATE_3
4)Create the Far Sync Instance Control file, copy it to FSI Server, and mount
A special privilege "SYSDG" has been introduced to simplify Dataguard operations.
Far Sync Instance
A New Standby destination type is allowed in Active Dataguard environment that ensures zero data loss failover and zero performance impact on Primary Database, is called "Far Sync Instance". This destination contains parameterfile, controlfile, and standby redo logs (SRLs), it receives the redo from Primary Database, and archives it to local destination through Standby Redo Logs. There are no Datafiles here. Technically, A Standby Database Instance without Datafiles is called Far Sync Instance. A far sync instance consumes very little disk and processing resources, yet provides the ability to failover to a terminal destination with zero data loss, as well as offload the primary database of other types of overhead (for example, redo transport).
To setup Far Sync Instance:
(Same as configuring Dataguard except backup/restore operations of the Primary Database)
1)Create pfile from spfile of the Primary, and copy to to Far Sync Server, and start the Instance
2)Add the Far Sync Destination, EX: "CDBFS"(Net Service Name/DB_UNIQUE_NAME), to Dataguard configuration (under LOG_ARCHVE_CONFIG=DG_CONFIG)
3)Set a new destination parameter to enable Log Transport Services, EX: LOG_ARCHIVE_DEST_3 & LOG_ARCHIVE_DEST_STATE_3
4)Create the Far Sync Instance Control file, copy it to FSI Server, and mount
SYS@CDB AS SYSDBA 28-OCT-13> ALTER DATABASE CREATE FAR SYNC INSTANCE CONTROLFILE AS '/fra/control01.ctl';
Database altered.
5)FSI can now receive the redo by enabling its destination on primary- Maximum Availability mode now allows SYNC mode with "NOAFFIRM" transport
- All DDL SQL's for recovery, role transitions etc.. can only be executed on ROOT Container.
- A Role transition(Switchover/Failover/Snapshots Standby etc..) is applicable to the entire CDB.
- A PDB can also be opened in READ ONLY mode on Standby irrespective of its state on Primary.
SQl> ALTER DATABASE SWITCHOVER TO CDBDR VERIFY;
Now Switchover operation is more simplified.
To Switchover:
1)Verify the Switchover possibility as explained above
2)Switchover
On Primary (Make it Physical Standby)
SQL> ALTER DATABASE SWITCHOVER TO CDBDR;
On Standby
SQL> ALTER DATABASE OPEN;
On Primary
SQL> STARTUP
SQL>ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE DISCONNECT FROM SESSION;
On Standby
SQL> ALTER SYSTEM SET LOG_ARCHIVE_DEST_STATE_2=ENABLE;
- DML operations on Temporary tables now permitted on Standby Database in Active Dataguard mode and also use of sequences.
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