ArcSDE is an extension created to integrate Spatial Database Engine (SDE) client/server technology within ArcInfo software. Users access ArcSDE through Defined Layers, a standard ArcInfo utility available at Version 7.2.
Two separate serversSDE for Coverages and SDE for DBMSmake up ArcSDE. SDE for Coverages serves data from file-based data sources as SDE layers. These sources include coverages, ArcView GIS shapefiles, ArcStorm layers, and map library layers. SDE for DBMS serves SDE layers stored in a relational database.