Forum Discussion
The leading dot is optional in OID addresses. It used to be required by RFC1213 standards IIRC, but newer software libraries have accounted for people leaving off the dot. Ours is also one that tolerates omitting the leading dot. This is otherwise known as a "fortunate typo".
Let's lay down some terminology so we make sure we're all talking about the same things:
Arista_Voltage_Sensors <- this is the name of the datasource.
Arista Voltage Sensors <- this is the display name of the datasource. It shows up directly under the device in the resource tree.
PowerSupply1 (or 2) <- this is the instance group. In this case, the group is created based on the value of auto.sensor_owner on the instance.
Input Voltage Sensor (100711104) <- this is the instance, you'll have one instance per sensor.
Voltage Sensor Overview <- this is an "overview" graph, meaning that it shows data from all sensors on the device. In this case, one line per instance.
Volts <- this is technically the overview graph datapoint name, which in this case is the same as the datasource's datapoint name.
As I understand your ask: you want to put a custom threshold on the volts datapoint, but only have that threshold apply to instances where the instance group starts with "PowerSupply". There may be other sensors, but they may not be in an instance group called "PowerSupply" and you don't want those sensors to generate an alert when the voltage is 0. Is that correct?