Encompass: Managing Functionality

Today's system management tools focus on a computer as a visible enclosure of both computational resources (CPU and memory) and the functionality and data that reside in the storage subsystem. Recent technological trends, such as shared SAN or NAS storage and virtualization, have the potential to break this tight association between functionality and machines. We describe the design and implementation of ENCOMPASS - an image management system centered around a shared storage repository of "master system images", each representing different functionality. The functionality is provisioned by "cloning" master images, associating the resulting "clone images" with specified physical and/or virtual resources ("machines"), customizing the clone images for the specific environment and circumstances, and automatically performing the necessary operations to activate the clones. "Machines" $physical or virtual - are merely computational resources that do not have any permanent association with functionality. ENCOMPASS supports the complete lifecycle of a system image, including reallocation and re-targeting of resources, maintenance, updates, etc. It separates image creation from image management from resource allocation policies - an emerging trend that is manifested in particular by proliferation of turn-key "virtual appliances".