ORAID——The implementation of a new data storage mode

A system concept called ORAID(Optical Replicated Arrays of Independent Disks) was presented in which the hard disks and optical media were converged into high performance WORM(Write Once Read Many) appliances in a way so that no additional tier was added to the existing storage system architecture. An ORAID product typically includes a full-range of non-redundant hard disk array on the front end and an optical library in the background where the optical library is hidden and therefore invisible to the user interface. The hard disk array can be formed as a NAS(Network Attached Storage) merged together with a database-driven hidden library. The user can access their file systems as usual with all the ease and comfort without additional integration efforts. ORAID effectively uses the lifetime of each individual hard disk in the array so the data migration overhead and the data loss risk can be significantly reduced. Unlike the conventional redundant technologies like RAID(Redundant Arrays of Independent Disks) or erasure coding where the number of defective disks allowed is limited, there is no correlation between the hard disks, and data on an ORAID system will never be lost no matter how many HDDs (Hard Disk Drives) are defect. Because of its physical nature the WORM/compliance will be ensured for optical media and this feature can also be realized for the hard disk front end by using HASH coding. In case of disk failure or any HDD absence the related data on the optical media will be automatically activated so that the data availability will be guaranteed when hard disks are somehow not accessible, e.g. during the hard disk rebuild process or replacement work. In an ORAID system, data on HDD and optical media is mutually protected. A health check process is keeping the integrity and safeguards against media failure. ORAID implements an integrated hybrid media storage in which the explicit backup process can also be eliminated. The logical consequence of greatly reduced workload for the optical drives and robotics will lead to less maintenance overhead on the library side and significant improvement of the working lifetime of the optical drives.