Timer is DB base .Below tag is from Domain.xml

<database-data-store name="clustered-store" datasource-jndi-name="java:/MyDS" partition="timer" database="postgresql" />

and for both Xa and NonXa data source , if db connection gets restarted then it will not recover.

Logs:

2020-12-22 20:17:27,426 ERROR [org.jboss.as.ejb3.timer] (Timer-1) WFLYEJB0456: Failed to refresh timers for in_my_upgrade.business.MyOutputMessageTimerBeanJMS

Caused by: org.postgresql.util.PSQLException: Connection to localhost:5433 refused. Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections.

Caused by: java.net.ConnectException: Connection refused: connect