Activation or Failover or Promotion of standby postrgeSQL cluster will make the standby cluster accessible in read-write mode to your application(s). You can execute the Activate standby in case your primary server or cluster is completely down or when performing a DR Test.
1. Concept
This process can be run also in case primary cluster isn’t accessible at all. The Activation is irreversible process.
Activation process is the same for WAL Streaming and WAL shipping configurations
The Activation process has following steps:
A. Disable Observer for the configuration
B. Promote Standby PostgreSQL cluster
C. Execute User Script (Optional)
2. Standby Activation
To activate your standby PostgreSQL cluster, select Activate Standby from ACTIONS pane:
On following screen you’re able to see the Activation readiness status (1), select User scripts to be executed post Activation (2) and start the Activation process (3).
When ready, click on Activate and confirm that you want to proceed. After activation completes, the configuration in dbvcontrol dashboard will be in “IN FAILOVER STATE” status and former standby server will be promoted to primary:
3. Recover from Standby Activation
Recovery from Standby Failover is semi-automated process where user needs to perform several steps.
A. Stop and delete the old primary PostgreSQL cluster
This can be done for example by running on old primary server:
/usr/pgsql-16/bin/pg_ctl -D /var/lib/pgsql/16/data stop
Once the instance is stopped, delete the old primary data files:
rm -rf /var/lib/pgsql/16/data/*
Old primary cluster should have status “NOT PRESENT” in the dashboard afterwards:
B. Recover the configuration from failover
In the ACTIONS pane, click on recover from failover (1) and confirm the action (2):
The configuration will then be reversed to the state as it was before creating PostgreSQL DR cluster:
C. Reinstate the old primary PostgreSQL cluster as standby
Proceed with steps in Creating PostgreSQL Standby Cluster to reinstate the old primary database as standby. Once finished, the replciation will be established in the opposite direction as before switchover:
D. Perform graceful Switchover
Follow steps in Graceful Switchover in order to reverse the replication and get back to the original state as it was before the activation. After switchover, the configuration will have following state in the dashboard:
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