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Geneos Rule how to use the Previous value and what is the alternative for Previous value function? Rate function
This function allows you to use the previous value when creating a rule. It can be used to compare the previous and current values for setting alerts or performing computations in the active console.
However, the previous value has limitations. The detailed process of the ‘previous’ function allows access to the value from the last time the rules were run, and not the last time the value changed. For a given rule evaluation, ‘previous’ will access the previous value of the attribute whose change triggered that rule evaluation. For any other attribute, ‘previous’ will access the current value of the attribute.
To provide an alternative way of doing computation and severity alerts, ITRS created another function called ‘Rate()’. With this new function, computation and comparison of dynamic data are now possible. We can also say that this new function is superior to its predecessor, the previous value.
Previous value example command.
if previous value <> value severity ok
else severity
endif
this example command will not work properly because the access to the value can only be read the last time the rule ran. As a result, the outcome of the command will only show “severity: OK.”
example of Rate() function
if rate(value) = 0 then delay 60 severity critical else severity ok endif
Now, let’s consider this rule that checks the value of the cell using the rate of change function ‘Rate()’. If there are no changes (the rate of change will yield 0), it will introduce a delay of 1 minute (60 seconds). After the delay, if the value still did not change, it will be tagged as “severity: Critical.”
In addition, as soon as the rule has finished and the state of the system has been changed then the rule will be re-evaluated, and since the value has not changed, the severity will be immediately returned to ok. In this case, the severity change may not be visible to the user.
Geneos rules, action and, alerts: https://docs.itrsgroup.com/docs/geneos/current/Gateway_Reference_Guide/geneos_rulesactionsalerts_tr.html#_Re-evaluating_Rules
Reference about the Rate() Function: https://support.itrsgroup.com/hc/en-us/articles/115004029809-Geneos-How-does-the-rate-function-work-in-the-Gateway-Rules-
if you plan to compare the timestamp with the current time you can use this command in the documentation: