1. A method of building a virtual representation of the performance of a data storage resource forming part of a networked electronic data store, the method comprising: representing the data storage resource as a plurality of separate virtual storage components, each virtual storage component representing a part of the data storage resource and having at least one operational state selectable from a pool of operational states; obtaining resource profile data from the data storage resource; and modelling the performance of said data storage resource by assigning, from said pool, an operational state to each virtual storage component to fit the resource profile data to generate a virtual representation of the data storage resource.