Design and implementation of an ultra-large scale automatic optical disc library

More and more digital information needs long term preservation, a cost-efficient storage system is needed to ensure long term data availability. Using tape and hard disk as storage medium can not meet the demands of long-term data preservation. Current blu-ray inorganic disc is able to store data more than 50 years, the fact that the drive and optical disc is separate makes it easy for optical disc to be stored. Optical disc is proved to be a choice for long term preservation. But the capacity of optical disc is too small compared to tape and hard disk, which limits its use in archival storage system. A novel large-scale Automation optical library system is introduced, a standard rack contains more than 10 000 discs, provides 1 GB/s throughput. The fundamental thought is tiered storage with HDD, SSD and optical disc and storage virtualization. HDD and SSD works as cache for optical storage level, thus improve performance; all the optical discs are set to a virtual volume pool. Optical library system implements automatic mechanical dispatch, file access and disc recording by the integration design controll and inner data structure. A common file system interface is provided to users. Experiments result shows that the system can automatically read and record files.