In this Document
APPLIES TO:
Oracle Database - Enterprise Edition - Version 12.1.0.1 to 12.1.0.1 [Release 12.1]
Information in this document applies to any platform.
GOAL
This Document offers Step by Step method to perform Switchover using Dataguard Broker command prompt DGMGRL.
SOLUTION
SWITCHOVER Considerations:
-
DG Broker will not downgrade the PROTECTION mode during the process of Switchover.
-
Configure suitable REDO transport mode on current standby that becomes Primary after switchover.
-
Configure SRL (Standby Redo Logs) and local archiving destination on current Primary.
Broker switchover command verifies the availability of SRL on current Primary Database and suitable Redo transport method on current Standby.
DB Restart Considerations:
-
If the switchover target is Physical Standby then Broker shutdown the Primary as a process of switchover.
-
If the switchover environment in MAX_PROTECTION mode and primary has only one Standby then broker shuts down both primary and standby as a process of switchover. If primary has multiple standby then broker shuts down only the new Primary.
I. Pre-Switchover Checks
Verify Dataguard Broker Configuration
Use following command s to verify broker status before switchover.
DGMGRL>show configuration;
DGMGRL>show database ;
DGMGRL>show database ;
DGMGRL>show database verbose ;
DGMGRL>show database verbose ;
For example,
Dg Configuration name =12c
Primary db_unique_name = boston
Standby db_unique_name =chicago
DGMGRL> show configuration;
Configuration - 12c
Protection Mode: MaxPerformance
Databases:
boston - Primary database
chicago - Physical standby database
Fast-Start Failover: DISABLED
Configuration Status:
SUCCESS
DGMGRL> show database boston;
Database - boston
Role: PRIMARY
Intended State: TRANSPORT-ON
Instance(s):
boston
Database Status:
SUCCESS
DGMGRL> show database chicago
Database - chicago
Role: PHYSICAL STANDBY
Intended State: APPLY-ON
Transport Lag: 0 seconds (computed 1 second ago)
Apply Lag: 0 seconds (computed 1 second ago)
Apply Rate: 0 Byte/s
Real Time Query: ON
Instance(s):
chicago
Database Status:
SUCCESS
NOTE : Further troubleshoot use,
DGMRL>show database ‘<>’ logxptstatus;
DGMGRL>show database ‘<> ‘inconsistentlogxptprops’;
Validate Database
Validate database verify following, no need to explicitly check whether ORLs/SRLS cleared.
-
Whether there is missing redo data on a standby database
-
Whether flashback is enabled
-
The number of temporary tablespace files configured
-
Whether an online data file move is in progress
-
Whether online redo logs are cleared for a physical standby database
-
Whether standby redo logs are cleared for a primary database
-
The online log file configuration
-
The standby log file configuration
-
Apply-related property settings
-
Transport-related property settings
DGMGRL> validate database boston
Database Role: Primary database
Ready for Switchover: Yes <-----------Redy for Switchover
Flashback Database Status:
boston: Off
DGMGRL> validate database chicago
Database Role: Physical standby database
Primary Database: boston
Ready for Switchover: Yes <--------This confirms Switchover readiness
Ready for Failover: Yes (Primary Running)
Flashback Database Status:
boston: Off
chicago: Off
Future Log File Groups Configuration:
Thread # Online Redo Log Groups Standby Redo Log Groups
(chicago) (boston)
1 4 4
NOTE : For further troubleshoot use validate database verbose.
DGMGRL>validate database verbose boston
DGMGRL>validate database verbose chicago
Preset Redo Transport related parameter
Verify below parameters are set based on PROTECTION MODE.
LogXptMode, NetTimeout, StandbyArchiveLocation, AlternateLocation, and RedoRoutes.
II SWITCHOVER
Disable Apply Delay
To increase the speed of switchover disable delaymins property.
DGMGRL>edit database chicago set property delaymins=0;
Turn on Data Guard tracing on primary and standby
DGMGRL> edit configuration set property tracelevel=support;
DGMGRL> edit database boston set property LogArchiveTrace=8191;
DGMGRL> edit database chicago set property LogArchiveTrace=8191;
Tail Alert Logs and DRC (optional) on all instances
Tail alert log and DRC log which is present in same location of alert log(text) from all the nodes of primary and standby.
tail –f
tail –f
tail –f log of primary>
tail –f log of standby>
Perform Switchover
Connect to sysdg
DGMGRL> connect sysdg
Password:
Connected as SYSDG.
DGMGRL> switchover to chicago
Performing switchover NOW, please wait...
Operation requires a connection to instance "chicago" on database "chicago"
Connecting to instance "chicago"...
Connected as SYSDBA.
New primary database "chicago" is opening...
Operation requires startup of instance "boston" on database "boston"
Starting instance "boston"...
ORACLE instance started.
Database mounted.
Database opened.
Switchover succeeded, new primary is "chicago"
--------------Primary Alert log- alert_boston.log--------------
ALTER DATABASE SWITCHOVER TO 'chicago'
Starting switchover [Process ID: 10402]
ALTER DATABASE COMMIT TO SWITCHOVER TO PHYSICAL STANDBY [Process Id: 10402] (boston)
.
Switchover End-Of-Redo Log thread 1 sequence 131 has been fixed
Switchover: Primary highest seen SCN set to 0x0.0x310a3a
ARCH: Noswitch archival of thread 1, sequence 131
ARCH: End-Of-Redo Branch archival of thread 1 sequence 131
ARCH: Evaluating archive log 1 thread 1 sequence 131
.
Switchover complete. Database shutdown required
Completed: ALTER DATABASE SWITCHOVER TO 'chicago'
--------------Standby Alert log - alert_chicago.log------------
SWITCHOVER: received request 'ALTER DTABASE COMMIT TO SWITCHOVER TO PRIMARY' from primary database.
ALTER DATABASE SWITCHOVER TO PRIMARY (chicago)
.
Standby became primary SCN: 3213880 <----------Record this SCN
.
Switchover: Complete - Database mounted as primary
SWITCHOVER: completed request from primary database.
----------------Primary Drc log -"/u01/app/oracle/diag/rdbms/boston/boston/trace/drcboston.log"-----------
SWITCHOVER TO chicago
.
Broker Configuration: "12c"
Protection Mode: Maximum Performance
Fast-Start Failover (FSFO): Disabled, flags=0x0, version=0
Primary Database: chicago (0x02010000) <-------Chicago as Primary
---------------Standby DRC log - "/u01/app/oracle/diag/rdbms/chicago/chicago/trace/drcchicago.log"--------------
Notifying Oracle Clusterware to prepare target standby database for switchover
Notifying DMON of db close
Notifying RSM0 of db close
.
Deferring associated archivelog destinations of sites permanently disabled due to Switchover
Notifying Oracle Clusterware to buildup primary database after switchover
III. Post-Switchover Steps
Reset Delaymins property
Change the delaymins property to prior on new standby after switchover based on business requirement.
DGMGRL> edit database set property delaymins=;
Set Trace to Prior Value
DGMGRL> edit configuration reset property tracelevel ;
DGMGRL> edit database boston reset property logarchivetrace;
DGMGRL> edit database chicago reset property logarchivetrace;
Verify Broker Configuration
DGMGRL> show configuration;
Configuration - 12c
Protection Mode: MaxPerformance
Databases:
chicago - Primary database
boston - Physical standby database <-----Boston is Physical Standby
Fast-Start Failover: DISABLED
Configuration Status:
SUCCESS
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