Performing PDB Switchover

A PDB switchover is a role reversal between the source PDB and its designated target PDB. Use DGMGRL commands to perform a PDB switchover.

How Broker Performs Switchover in a DG PDB Environment

The broker performs the following actions when you start a switchover:

  1. Verifies that the specified target database is reachable, the target PDB exists, and the target PDB is a designated DG PDB.

  2. Validates that the source PDB and target PDB are in the correct states. The source PDB must be open in read/write mode and the target PDB must be in recovery mode.

  3. Confirms that the target PDB is recovering the current redo stream of the source PDB.

  4. Closes the source PDB on all instances.

  5. Converts the source PDB to the standby role. After the switchover completes, the source PDB will become the target PDB.

  6. Converts the target PDB to the primary role, after the target PDB has recovered through the all the redo generated by the source PDB and recovery is canceled.

  7. Opens the target PDB as the new source PDB.

  8. Starts recovery after redo from the target PDB is registered at the original source PDB.

Starting a Switchover to a PDB

When a switchover is started, the source PDB and target PDB must have as small a redo lag as possible.

To start a PDB switchover:

  • Run the SWITCHOVER PLUGGABLE DATABASE command. Specify the name of the PDB that must now perform the primary role.

The broker controls the rest of the PDB switchover.

Example 7-1 Performing a PDB Switchover

In this example, a switchover is performed between the bos_sales and nyc_sales PDBs. After the switchover operation completes, the target PDB nyc_sales in the target database newyork transitions to the primary role and becomes the new source PDB. 

DGMGRL> SWITCHOVER TO PLUGGABLE DATABASE nyc_sales AT newyork; 
Verifying conditions for Switchover... 

  Source pluggable database is 'BOS_SALES' at database 'boston' 

Performing switchover NOW, please wait... 

  Closing pluggable database 'BOS_SALES'... 
  Switching 'BOS_SALES' to standby role... 
  Waiting for 'NYC_SALES' to recover all redo data... 
  Stopping recovery at 'NYC_SALES'... 
  Converting 'NYC_SALES' to primary role... 
  Opening new primary 'NYC_SALES'... 
  Waiting for redo data from new primary 'NYC_SALES'... 
  Starting recovery at new standby 'BOS_SALES'... 

Switchover succeeded, new primary is "NYC_SALES"