The Data Architecture Policy is a design document that proposes what data should be stored where - whether on device, on your backend server, or on the PDA. the policy is a design artefact that will impact on compliance, data protectiom impact assessment and privacy impact assessments. Getting the data architecture policy right for your system means less problems later. The data architecture policy weighs the tradeoffs of privacy, security, costs and performance when decided what personal data should be placed at which location for your application.