The Process Engine Database is a Microsoft SQL or Oracle database that manages the process data.
Workflows are data in the Process Engine Database. If the database is not working or properly configured, workflow activity is impossible.
Isolated Region – a logical subdivision or partition of the Process Engine Database that separates work according to organizational boundaries. Each Process Engine Database must contain at least one isolated region.
Roster – a table that contains information about all currently running workflows that is used primarily to search for active workflows.
Queue – a table that holds work items.
Workflow – an instance of a workflow definition.
Work Item – a single unit of work; a task.
The Process Engine Database is administered through the Process Configuration Console (PCC), which is available through FileNet P8 Workplace. The PCC is used to create and initialize isolated regions, and create queues and rosters.
source: IBM Corporation