A distributed storage system can maintain calculated load values of services throughout the system. The load values represent different types of load on the system. When a load value corresponding to a client changes, the load value is evaluated against thresholds to determine whether a different quality of service (QoS) policy is to be selected and implemented. If so, a function/formula indicated in the selected policy is used to calculate a scaling factor, which is then used to calculate a target performance value based on QoS parameters of the client. The system then manages access by the client according to the target performance value.