Data archiving and distribution of the Virgo antenna for gravitational wave detection

We describe the architecture of the Data Archiving and Distribution of the Virgo antenna for gravitational wave detection. The main characteristic of this system is the modularity of the architecture, which allows to upgrade it following the progress of the technology without dramatic changes in the hardware and software components. Its main performances are: 1. raw data archiving at a maximum sustained data flow of 10 Mbyte/s on DLT tapes (35/70 Gbyte); 2. data archiving capacity on disk up to 1 Tbyte at a maximum sustained data flow of 25 Mbyte/s for the online data distribution; 3. data retrieval for on-line distribution up to 10 Mbyte/s. The basic architecture of the system consists of two sections: an acquisition and storage section and a data management section. The former is a LynxOS based system with the disks directly connected to the CPU slave boards, the latter is a DEC-Unix Alpha Server (Data Server), which NFS mounts the LynxOS disks through a Fast Ethernet network