What is the criterion used behind Rule definition condition #DSDirectoryReadsPersec# > 8 for Active Directory rule LDAP DS Directory Reads/sec
The attribute DSDirectoryReadsPersec represents "the number of directory reads per second
Microsoft does not have a recommended threshold value for this counter. The threshold can be different in different environments. Metrics that have no generally accepted thresholds for alarms are configured as trend alarms. The significance of trends is dependent on the environment and default settings may generate many meaningless alarms in a busy environment while failing to fire at all in a smaller environment. It is recommended that the administrator allow the agent to collect values over an adequate period of time to observe normal performance and then adjust trend alarms to fire at suitable thresholds.
Attached groovy script can be run in Script to calculate avg Directory Reads/sec value for each DC over past 30 days.