The NetScaler appliance designates a service as UP only when the sum of the weights of all monitors bound to it and that are UP is equal to or greater than the threshold value configured on the service. The weight for a monitor specifies how much that monitor contributes to designating the service to which it is bound as UP.
By default, the monitor threshold is set to 0 and monitor weights are set to 1. All monitors have equal weightage then and a service can go DOWN when any one of the monitors goes DOWN.
For example, assume that three monitors, named Monitor-HTTP-1, Monitor-HTTP-2, and Monitor-HTTP-3 respectively, are bound to Service-HTTP-1, and that the threshold configured on the service is three. Suppose the following weights are assigned to each monitor:
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The weight of Monitor-HTTP-1 is 1.
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The weight of Monitor-HTTP-2 is 3.
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The weight of Monitor-HTTP-3 is 1.
The service is marked UP only when one of the following is true: