This article discusses the percentage under alert parameters for resource alerts in DPA and its effect on alerting.
DPA 9.2 and later
Example: A resource that collects active sessions once every minute, thresholds are set to 100 (warning) and 200 (critical) and an alert is set based on active sessions as a resource metric and set the percentage to 75 with an alert interval of 10 minutes.
In the example, the thresholds had to have exceeded either the 100 or 200 for 75% of the collections for the alert to trigger. If you want to be alerted when it crosses the threshold, set the value to 1%. If you want to be alerted when it crosses the threshold for each collection interval, set it to 100%.