You can convert an asynchronous standby instance to a synchronous standby instance.
Converting an Asynchronous standby instance to Synchronous can cause the master instance to queue the incoming transactions until the standby instance is ready. For this reason, it is recommended that this operation be performed during a scheduled maintenance period.
When adding a synchronous standby instance, Fujitsu Enterprise Postgres will only keep the first entry in [Synchronous standby names] in synchronous state.
Follow the procedure below to convert an Asynchronous standby instance to Synchronous.
In the [Instances] tab, select the master instance of the relevant cluster.
Click 
.
In the [Streaming replication] section, edit the value for [Synchronous standby names].
Add the "Application name" of the standby instance you want to be in Synchronous mode.
Click 
.
Select the master instance and click 
.
Select the standby instance. [Instance type] will now show the updated status.
See
To learn more about the differences between synchronous and asynchronous standby modes and their behavior, refer to "Streaming Replication" in "High Availability, Load Balancing, and Replication" in the PostgreSQL Documentation.
