PADS: A Policy Architecture for Distributed Storage Systems

This paper presents PADS, a policy architecture for building distributed storage systems. A policy architecture has two aspects. First, a common set of mechanisms that allow new systems to be implemented simply by defining new policies. Second, a structure for how policies, themselves, should be specified. In the case of distributed storage systems, PADS defines a data plane that provides a fixed set of mechanisms for storing and transmitting data and maintaining consistency information. PADS requires a designer to define a control plane policy that specifies the system-specific policy for orchestrating flows of data among nodes. PADS then divides control plane policy into two parts: routing policy and blocking policy.