ESO's Next Generation Archive System

Early in July 2001, ESO installed prototype versions of the archiving and buffering units of the Next Generation Archive System (NGAS) at the 2.2 m telescope in La Silla. The two units are the on-site part of an archive system we are currently testing for high data rate/high data volume instruments like the Wide Field Imager which is mounted at the 2.2 m telescope. The NGAS concept is built around two ideas: the use of cheap magnetic ATA-100 disks as the archiving media, and highly flexible and modular software called NG/AMS, the Next Generation Archive Management System. The main goals of the whole system are scalability and the ability to process bulk data within the archive itself. In fact the NGAS scales in such a way that it is possible to process all of the data in. the archive within a constant time, where this constant time is of the order of one to a few days depending of the kind of processing required. In this paper we present an overview of the NGAS concept, the NGAS prototype implementation, and some of the experience we have gained during the first month of operating the system in a real observational environment. We also present the infrastructure of the main archive which supports scalable, decentralized processing, both of which are essential for large scale scientific programs submitted to a Virtual Observatory.