Wednesday, October 16, 2019

Data Guard Broker Support for DBMS_ROLLING Upgrades

Data guard broker can remain on during a DBMS_ROLLING upgrade and no need to disable it. In oracle 19c there are many enhancements for Data Guard Broker Support for DBMS_ROLLING Upgrades

• Data Guard broker support is enabled by using the DBMS_ROLLING.BUILD_PLAN procedure
• Before starting a DBMS_ROLLING upgrade the fast-start failover feature must be disabled.
• Role changes are permissible during when rolling upgrade is in progress.
• During rolling upgrade any attempt to enable fast-start failover is rejected.
• Broker support is enabled by default during execution of the DBMS_ROLLING.BUILD_PLAN procedure
• The broker prevents a role change to a standby which is not protecting the current primary. The role changes to the Trailing Group Standby are allowed before the switchover phase. After the switchover phase, role changes are only allowed to the Leading Group Standbys.
• The broker will notifies Global Data Services and Oracle Clusterware as appropriate during the rolling upgrade.
• If the upgrade target is an Oracle RAC database, then the broker automatically reduces the target standby to one instance during the start of the upgrade process and allows the upgrade to proceed. Without the broker, the start of the upgrade is rejected if target has multiple instances running.
• The switchover step during a rolling upgrade should be performed using the DBMS_ROLLING.SWITCHOVER procedure.
• The status of a rolling upgrade being done using the PL/SQL package DBMS_ROLLING and the information is displayed in the broker commands SHOW CONFIGURATION and SHOW DATABASE output.

Please see the output of SHOW CONFIGURATION, where you can see configuration status as ROLLING DATABASE MAINTENANCE IN PROGRESS

Configuration - DRSystem
Protection Mode: MaxPerformance
Members:
North_Sales - Primary database
South_Sales - Transient logical standby database
Fast-Start Failover: DISABLED
Configuration Status:
ROLLING DATABASE MAINTENANCE IN PROGRESS


Please see the output of SHOW Database , where you can see Database status as WARNING.

Database – DRNode1
Role: Physical standby database
Intended State: APPLY-ON
Transport Lag: ***
Apply Lag: ***
Average Apply Rate: ***
Real Time Query: OFF
Instance(s):
South
Database Warning(s):
ORA-16866: database converted to transient logical standby database for rolling
database maintenance
Database Status:
WARNING


Three are specific Requirements DBMS_ROLLING Upgrades on a CDB

• To use DBMS_ROLLING the database compatibility should be set to 12.2 or higher

• Different character sets pluggable databases in a CDB supported for upgrade using DBMS_ROLLING

• The TNS services referenced in the LOG_ARCHIVE_DEST_n parameters must be services that resolve to the root container of the destination database.

• The process assisting DBMS_ROLLING can only execute from the root container.

• While a DBMS_ROLLING upgrade is in progress, if any DDL is executed to start the install, upgrade, or patching of an container then you will get an error.

• When user attempt to start a DBMS_ROLLING upgrade when upgrade to an application container is in progress user will get an error. Before calling DBMS_ROLLING.SWITCHOVER all container databases on the transient logical standby must be plugged in and opened, this helps eliminating logical standby apply engine halt because it cannot apply to a given PDB.

Regards
Satishbabu Gunukula, Oracle ACE

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