New KEK central computer system (KEKCC) has been introduced in January 1996. The system has two SONY PetaSite tape libraries. Each library is equipped with eight or twelve SONY DTF (Digital Tape Format) helical scan tape drives. Each tape can store up to 42 GB of data.
Two PetaSite libraries are dedicated to four workstation clusters of separate research groups (``clusters''). PS Cluster, a cluster for KEK Proton Synchrotron experiment groups, has a PetaSite library of 12 TB with twelve DTF drives. The same library is shared with a cluster of another research group, JLC Cluster. Four DTF drives of the PS cluster and two drives of the JLC cluster are used for the HSM migration server. Another eight drives of the PS Cluster are used directly from the user processes. Another PetaSite system of 8 TB are connected to Central Cluster and International Collaboration Cluster. Each cluster has three DTF drives for HSM migration.