A storage area network (SAN) includes a plurality of digital data processors, each with a file system that effects access to one or more storage devices coupled to the SAN, for example, via an interconnect fabric. A process (e.g., executing on a manager digital data processor) responds to a file system over-extension notification from at least a selected one of the digital data processors, e.g., by assigning a further storage device to the selected digital data processor. The type of response is, more particularly, determined in accord with a hierarchically defined policy inherited, in whole or in part, from one or more hierarchical groups of which the digital data processor is a member.