1. Overview : 1.2 Open Loop and Closed Loop Implementation Models : 1.2.3 Closed Loop Versus Open Loop
1.2.3 Closed Loop Versus Open Loop
Open loop systems have many disadvantages due to their lack of feedback from the system. With feedback in a closed loop system, we can more closely manage the state of the system relative to desired goals, such as staying within an SLA or providing an appropriate end-user experience. Closed loop systems provide several advantages over open loop systems:
*Disturbance rejection from unforeseen increases in user load.
*Predictable performance with uncertain service models when a user does not know exactly how the service scales relative to user workload.
*Improved reference tracking where resource allocation can closely track what is needed to provide SLA compliance without overprovisioning.
Closed loop systems are recommended because of these benefits.