Actual and derived state

Each in a service model has an actual state and a derived state.

A device element's actual state is determined by events that occur on the device, regardless of the service models in which it participates. A service model member's actual state is generated from the service model in its own service context. The element's derived state is generated from policy propagation within a given context. In the Service Impact graph, the symbol that appears inside the node's border reflects the actual state; the border that outlines the node reflects the derived state.

In the following example graph, the actual and derived states are down. The parents of the device have a degraded and at-risk actual state, yet the derived state based on the contextual policy, is degraded.

Visual state indicators

The Impact View provides symbols and borders to visually indicate availability, actual state, performance, and derived state, as shown in the following table.
Availability Performance Symbol / Actual State Border / Derived State
UP ACCEPTABLE
ATRISK Not applicable.
DEGRADED DEGRADED
DOWN UNACCEPTABLE

A member's actual and derived states can be different. As shown in the following example, a service's actual state can be up, but an applied context policy changed its derived state to down.