The operation and use of a 2 terabyte optical archival store

The authors report on the operation and use of the Optical Archival Store (OAS), a very large archival storage system. The system uses a robot which moves optical disk cassettes to and from three read/write units. The software was designed to make the system very easy to use. The users or clients see the system as a large file server, and see the system as a single 2 terabyte (16 TB) volume with a 1 gigabyte file-length limitation. Thus the users concern themselves only with filenames and not with cassette numbers or track numbers. The system is automatic and available 24 h/day, seven days a week to a community of scientists in many university departments. The users pay for their use and can choose between the OAS, centralized magnetic disk systems, their own magnetic disks, and various magnetic tape systems. Use is voluntary, and the users make their choice in terms of the perceived values and perceived costs.<>