Oracle 12cR1 - How to Switchover In Multiple Physical Standby Environment With Cascaded Standby Scenario

Question

Current Environment:

• 12cR1 RAC Production Database -> Let's say PROD

• 12cR1 Single Instance Physical Standby (Active Data Guard) -> Let's say DR1

Planned Environment:

• 12cR1 RAC Production Database -> PROD (From current environment)

• 12cR1 Single Instance Physical Standby (Active Data Guard) -> DR1 (From current environment)

• 12cR1 RAC Physical Standby -> Let's say DR2 (New environment)

• 12cR1 Single Instance Physical Standby -> Let's say DR3 (Cascaded standby to DR2) (New environment)

Important Note: data guard broker will not be used. Process will be done manually.

Scenario:

We want to switchover to a new physical machine.

Physical machine and OS (OEL 8.7) installations have been completed. (New environment)

Oracle 19c grid software and Oracle 12cR1 database software installations have been completed. (New environment)

The goal here is to both move to a new physical machine and move to a newer operating system version. After the switchover to new environment, 12cR1 to 19c upgrade will be planned.

A few days before the migration, the data guard installation in the new environment will be completed. (Named DR2)

At the same time, the installation of DR3 data guard cascaded with DR2 will be completed a few days before the migration. (DR3)

Thus, at the time of migration, PROD will have 2 different data guards (DR1 and DR2). At the same time, DR3 is cascaded with DR2.

Our purpose in doing this is to complete the migration with minimum downtime. After switchover from PROD to DR2, we will convert DR3 from cascaded standby to physical standby (active data guard).

Questions:

I have 2 different questions.

1-) Is the scenario possible? While there are 2 different data guards (DR1 and DR2) belonging to PROD, how can I determine with commands whether switchover will be performed specifically to DR2 (without corrupting DR1)? Actually, DR1 does not matter during the migration, or should I remove DR1 from the data guard configuration before the switchover? (by deleting DR1 from parameters such as dg_config, fal_server, fal_client, log_archive_dest etc.)

2-) Is there any action that needs to be taken in DR3 before performing the switchover to DR2? Because it will work as cascaded standby until the moment of switchover. Or should I remove the cascaded standby configuration of DR3 before performing the switchover from PROD to DR2 and configure it as physical standby for the new PROD (old DR2) after the switchover? After the switchover, DR2 will become the new PROD and DR3 will become the new DR2 (active data guard)?

Answer 1

1. Yes, it is possible, done it hundreds of times. A switchover target is not chosen randomly. Without the broker, as part of the switchover steps, you manually convert and open the database you want to open as primary database. With the broker, you specify the switchover target in the switchover command. Use the broker. Much more comfortable than editing parameters and stopping/converting/starting databases manually.

2. Forget the cascaded standby, it would just make your life more difficult for nothing in exchange. Just configure the 2 new standby databases without cascading, so you would have 3 in total. And once again, use the broker for switchover. It will take care of all the configuration.