The report is showing current (the last data sample within the selected time range) data including connection time and response time.
The column "Availability (%)" in the report is displaying, how many of an instance/RAC components are available in percentage. For example:
RAC with 2 nodes:
The report would show the following data in the availability column:
- RAC 50%
- Node1 100%
- Node2 0%
If the report is for a stand-alone Oracle instance (not a RAC) and since only the current value is considered for the report display, “Availability %” column in the Instance Availability Report would always show 100%, when the DB is up when the report is generated
WORKAROUND:
As a an alternative please use the "Oracle Executive Workload Summary Report"
In this report you will get the period average of the DB availability under the "Operation Statistics -> DB Availability" section.