A method for routing an incoming service request is described wherein the
service request is routed to a selected storage tier based on that
selected storage tier having a predicted value indicating a state having
greater utility as compared with the predicted value of the state
associated with at least one other storage tier within the storage
system. A computer system comprising a multi-tier storage system is
described, the multi-tier storage system having a routing algorithm
configured to adaptively tune functions which map variables describing
the state of each storage tier of the storage system into the average
latency experienced by incoming service requests associated with the
storage tier.