What are the modes in always on?

What is availability mode in always on?

In Always On availability groups, the availability mode is a replica property that determines whether a given availability replica can run in synchronous-commit mode.

What is synchronous and asynchronous in always on?

Most synchronous replication products write data to primary storage and the replica simultaneously. As such, the primary copy and the replica should always remain synchronized. In contrast, asynchronous replication products copy the data to the replica after the data is already written to the primary storage.

What is failover in always on?

Always On Availability Groups monitors the health of both replicas in an automatic failover set. If either replica fails, the availability group's health state is set to CRITICAL. If the secondary replica fails, automatic failover is not possible because the automatic failover target is unavailable.

How do I change failover mode always on?

Expand the Always On High Availability node and the Availability Groups node. Click the availability group whose replica you want to change. Right-click the replica, and click Properties. In the Availability Replica Properties dialog box, use the Failover mode drop list to change the failover mode of this replica.