by From 12c onwards, Data Guard maximum availability supports the use of the noaffirm redo transport parameter. It enables Maximum Availability protection mode at larger distances with less performance impact then before. In “LogXptMode=FASTSYNC” mode, standby database returns receipt acknowledgment to its primary database as soon as redo is received in memory. The standby database does not wait for the Remote File Server (RFS) to write to a standby redo log file.
This is how FastSync set up:
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DGMGRL> show configuration Configuration - DGTST_HA Protection Mode: MaxAvailability Members: DGTST_PRIMY - Primary database DGTST_STBY - (*) Physical standby database Fast-Start Failover: ENABLED Configuration Status: SUCCESS (status updated 32 seconds ago) DGMGRL> show database 'DGTST_STBY' logxptmode LogXptMode = 'sync' DGTST:/oracle:>sqlplus sys/oracle@DGTST_PRIMY SQL*Plus: Release 12.1.0.2.0 Production on Mon Feb 19 13:33:34 2018 Copyright (c) 1982, 2014, Oracle. All rights reserved. Connected to: Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options CDB$ROOT@DGTST> show parameter log_archive_dest_2 log_archive_dest_2 string service="dgtst_stby", SYNC AFFIRM delay=0 optional compression=disable max_failure=0 max_connections=1 reopen=300 db_unique_name="DGTST_STBY" net_timeout=30, valid_for=(online_logfile,all_roles) DGMGRL> edit database 'DGTST_STBY' set PROPERTY LogXptMode=fastsync; Error: ORA-16654: fast-start failover is enabled Failed. DGMGRL> disable fast_start failover; Disabled DGMGRL> edit database 'DGTST_STBY' set PROPERTY LogXptMode=fastsync; Property "logxptmode" updated CDB$ROOT@DGTST> show parameter log_archive_dest_2 log_archive_dest_2 string service="dgtst_stby", SYNC NOAFFIRM delay=0 optional compression=disable max_failure=0 max_connections=1 reopen=300 db_unique_name="DGTST_STBY" net_timeout=30, valid_for=(online_logfile,all_roles) |
FarSync:
Oracle 12c introduced Far Sync Data Guard configuration which is a light-weight/remote standby database instance whose role is to receive redo synchronously from the primary database and forward the redo asynchronously to the other remote standby databases. Far Sync instance is a log transport “proxy” and it has to be located close to the primary database. The far sync instance just has a control file , standby redo logs and it archives the standby redo log files to local archive redo logs. This type of instance does not have any user data files so it means it cannot be opened for read access.
Data Guard Broker configuration is already there ( as described Here) and adding new Far Sync instance is quite easy task.
| Primary Database | DGTST_PRIMY |
| Remote standby databases | DGTST_STBY |
| Far sync | DGTST_FS |
Create directories: Create the following directories where you want to create the FarSync database instance.
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mkdir /oracle/admin/DGTST/adump mkdir /redolog/DGTST/ mkdir /ora_fra mkdir /ora_archive/DGTST |
Create Controlfile and pfile: Create a standby control file and pfile file from the primary database using the following syntax, and copy the control file, pfile and password file to the server were far sync will be configured.
Update parameters: Now update the parameter file with for FarSync instance. Only Data Guard related parameter need to be changed.
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#All parameters stay the same except following control_files='/oracle/admin/DGTST/control01.ctl' db_unique_name='DGTST_FS' log_archive_config='dg_config=(DGTST_PRIMY, DGTST_STBY,DGTST_FS)' fal_server='DGTST_PRIMY' log_file_name_convert='/redolog/DGTST','/redolog/DGTST' |
Now copy control file and parameter file to true location.
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cd /backup_store/DGTST_FS cp control01.ctl /oracle/admin/DGTST cp initDGTST_FS.ora /oracle/product/12.1.0.2/dbs |
Tnsnames.ora : entry “DGTST_FS” has to be added on primary and standby server as well along with FarSync server.
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DGTST_PRIMY = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = DGTST01)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = DGTST) ) ) DGTST_STBY = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = DGTST02)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = DGTST) ) ) DGTST_FS = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = DGTST04)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = DGTST) ) ) |
Now Far Sync instance can be started and new standby logs could be created. Make sure that Data Guard Broker has been started as well.
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sqlplus / as sysdba SQL*Plus: Release 12.1.0.2.0 Production on Mon Feb 19 16:20:34 2018 Copyright (c) 1982, 2014, Oracle. All rights reserved. Connected to: Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options idle> startup mount ORACLE instance started. Total System Global Area 2147483648 bytes Fixed Size 2926472 bytes Variable Size 553650296 bytes Database Buffers 1577058304 bytes Redo Buffers 13848576 bytes Database mounted. idle> select database_role from v$database; DATABASE_ROLE ---------------- FAR SYNC idle> alter system set dg_broker_start=TRUE Scope=both; |
Update following parameter at Primary and standby database.
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sqlplus sys/oracle@DGTST_PRIMY CDB$ROOT@DGTST> alter system set log_archive_config='dg_config=(DGTST_PRIMY, DGTST_STBY,DGTST_FS)'; System altered. sqlplus sys/oracle@DGTST_STDBY CDB$ROOT@DGTST> alter system set log_archive_config='dg_config=(DGTST_PRIMY, DGTST_STBY,DGTST_FS)'; System altered. |
Broker will be used to do all configuration work. You should connect to Broker from primary database.
Note: Don’t set any log_arch_dest_n. DGBroker will take care that.
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DGMGRL> connect sys/oracle DGMGRL> add far_sync DGTST_FS AS CONNECT IDENTIFIER IS DGTST_FS; far sync instance "dgtst_fs" added DGMGRL> show configuration Configuration - DGTST_HA Protection Mode: MaxAvailability Members: DGTST_PRIMY - Primary database DGTST_STBY - (*) Physical standby database dgtst_fs - Far sync instance (disabled) Fast-Start Failover: ENABLED Configuration Status: SUCCESS (status updated 51 seconds ago) DGMGRL> edit database 'DGTST_PRIMY' set property redoroutes='(local : dgtst_fs sync)'; Error: ORA-16900: change of LogXptMode or RedoRoutes property violates overall protection mode Failed. #Need to disbale the fast_start and protection mode. DGMGRL> disable fast_start failover; Disabled. DGMGRL> EDIT CONFIGURATION SET PROTECTION MODE AS MAXPERFORMANCE; Succeeded. DGMGRL> edit database 'DGTST_PRIMY' set property redoroutes='(local : dgtst_fs sync)'; Property "redoroutes" updated DGMGRL> edit far_sync 'dgtst_fs' set property redoroutes='(DGTST_PRIMY:DGTST_STBY)'; Property "redoroutes" updated DGMGRL> enable far_sync dgtst_fs Enabled. # Now you can switch protection mode. DGMGRL> EDIT CONFIGURATION SET PROTECTION MODE AS MAXAVAILABILITY; Succeeded. DGMGRL> enable fast_start failover; Enabled. DGMGRL> show configuration Configuration - DGTST_HA Protection Mode: MaxAvailability Members: DGTST_PRIMY - Primary database dgtst_fs - Far sync instance DGTST_STBY - Physical standby database Fast-Start Failover: ENABLED Configuration Status: SUCCESS (status updated 56 seconds ago) |
Above configuration is sending redo data from primary database to far sync instance using SYNC mode and redo data from far sync instance to standby database using ASYNC mode. As primary and far sync instance are close one to each other you can have no data loss mode without additional network synchronization overhead.
I hope this is help for you.
Mandy!!!!
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