The volman system is responsible for keeping track of the tapes, and for bringing them on line when requested. It was designed to support the mass storage systems deployed here at NAS under the NAStore 2 system. That system supported a total of twenty StorageTek NearLine tape silos at two locations, each with up to four tape drives each. Each silo contained upwards of 5000 tapes, and had robotic pass-throughs to adjoining silos.
The volman system is designed using a client-server model, and consists of three main components: the volman master, possibly multiple volman servers, and volman clients. The volman servers connect to each tape silo, mount and unmount tapes at the direction of the volman master, and provide tape services to clients. The volman master maintains a database of known tapes and locations, and directs the tape servers to move and mount tapes to service client requests. The client component consists of a set of programs to monitor activity and tape quotas, and a programmatic interface so that programs can make requests of the volman master and servers.