PDE is a parallel operating system. It utilizes services in each node's local OS for normal OS functions (memory management, scheduling, IO,...). PDE implements a virtualizing environment on top of those services called VProcs which allow many AMPs to be run on each node and manages the configuration. On top of that it provides parallel services such as global addressing for AMPs, point to point, broadcast and AMP group messaging, global semaphores, system startup and shutdown, failure detection and recovery, ... . Teradata Database only uses PDE services which makes PDE also a portability layer insulating the database from details of the underlying operating system and platform - allowing the database to operate on a wide variety of purpose built and cloud configurations.