Dataguard cascading standby (1 drag n mode)

After the Oracle11.2.0.2 version, Dataguard supports cascading mode transfer logs, which can be transferred from a to B,b to C,b to D, and so on, with endless

Cascading standby can share the pressure of the main library to transfer logs to multiple repositories.

A cascading standby can transfer logs to up to 30 standby libraries, which can make physical standby, logical standby, and any one of the snapshot standby.

Cascading standby will have a certain delay, because cascading action is not the main library issued, but cascading standby library received the main library log, the local archive standby log, log can be cascaded to other standby library, For the previously mentioned log can be from a to b,b to C,b to D, this cascading standby library is b library, Cascade Standby Library refers to C,d.

Cascading standby Configuration ideas:
1. Select a physical standby to prepare the configuration cascading standby

2.cascading standby Fal_server points to the main library or standby library that receives logs directly from the main library

3.cascading STANDBY Configuration Log_archive_dest_n service points to STANDBY library to cascade the transport log, valid_for parameter write (standby_logfiles,standby_role),
Sync or Async parameters will be ignored.

4. In the cascaded standby library, Fal_server points to cascading standby or other standby that get logs directly from the main library. Of course, cascaded Standby library Fal_server can also point to the main library, then it will be treated as cascading standby.

5. The following configuration instance, the main library is Boston, the physical standby boston2 (cascading standby), the physical standby Denver (cascaded standby)

5.1.Primary Database
———————————————————-
Db_unique_name=boston

Fal_server=boston2

Log_archive_config= ' dg_config= (boston,boston2,denver) '

Log_archive_dest_1= ' Location=use_db_recovery_file_dest
Valid_for= (all_logfiles,all_roles) Db_unique_name=boston '

Log_archive_dest_2= ' Service=boston2 SYNC
Valid_for= (Online_logfiles,primary_role) db_unique_name=boston2′

5.2.Cascading Physical Standby Database
———————————————————-
Db_unique_name=boston2

Fal_server=boston

Log_archive_config= ' dg_config= (boston,boston2,denver) '

Log_archive_dest_1= ' location= use_db_recovery_file_dest
Valid_for= (all_logfiles,all_roles) db_unique_name=boston2′

Log_archive_dest_2= ' Service=denver
Valid_for= (standby_logfiles,standby_role) Db_unique_name=denver '

5.3.Cascaded Physical Standby Database
———————————————————-
Db_unique_name=denver

Fal_server=boston2

Log_archive_config= ' dg_config= (boston,boston2,denver) '

Log_archive_dest_1= ' location= use_db_recovery_file_dest
Valid_for= (all_logfiles,all_roles) Db_unique_name=denver '