The database client fault probe queries the dynamic performance view v$sysstat to obtain database performance statistics. Changes to these statistics indicate that the database is operational. If these statistics remain unchanged between consecutive queries, the fault probe performs database transactions to determine if the database is operational. These transactions involve the creation, updating, and dropping of a table in the user table space.
The database client fault probe performs all its transactions as the Oracle user. The ID of this user is specified during the preparation of the nodes as explained in How to Prepare the Nodes.
The probe uses the time-out value that is set in the resource property Probe_timeout to determine how much time to allocate to successfully probe Oracle.