Elisabetta Angeloni, Allan Brighton, Fabio Sogni, Miguel Albrecht (ESO)
The ESO Very Large Telescope (VLT) will deliver a Science Archive of astronomical observations well exceeding the 80 Terabytes mark already within its first six years of operations. In order to support the maximum scientific exploitation of the archive, ESO has developed and is currently enhancing the On-Line Archive System (OLAS) that captures new data and supports the later massive processing of archive data for Archive Research Programmes. The system is a multi-tasking application written in C++ running on a WAN of heterogeneous UNIX platforms. It is a very flexible and fault-tolerant tool that keeps the data produced by the telescopes, processes them in real-time and stores summary information in a catalog available to the large public through the Web as well. Data is kept on safe storage with RAID arrays until it has been successfully put on long-term storage media by the Archive Storage System (ASTO) with DVD-ROM Jukeboxes (ESO has been one of the first organisation to deploy this new technology!). Moreover, the system allows astronomers to retrieve and process several kind of data: from raw and reduced FITS frames to meteorological data and operations log files. Data is retrieved from distributed databases both in real-time and deferred mode with transparent replication across sites.