The Data Access Layer for D0 Run II: Design and Features of SAM

The Sequential Access Model, or SAM, is the data access layer being built for Run II data handling at Dzero. An overview of the Dzero data handling system and a description of the data access software being built are given. At the center of the data management system is an RDBMS which is used to track file-based data and trace processing steps and usage patterns. The procedures by which data is added to the system and distributed to users are described. SAM is a functioning system and much operational experience has been gained running it. Additional features are planned to be added before the Fermilab collider run begins in spring of 2001.