Reliability Model for Data Storage on Modern Libraries of Optical Disks United in RAID-6

The article focuses on the problem of ensuring the reliability of long-term storage of archival information on robotic libraries, optical disks when these drives are combined in RAID-6. The study proposes the following organization of
the disk memory, in particular for Panasonic in its modern library of optical discs LB-DH8. In the library the information is stored on a cartridge, each containing 12 optical disks that can be configured for RAID-6. We built a mathematical model of reliability of information storage on optical disks for RAID-6 with a different number of disks. We propose an acceptability criterion for probability value of loss of information stored in the library, and the probability of information loss in the library should not exceed the probability of failure of one optical disk. For example, calculations for robotic library Panasonic LB-DH8 show that to ensure the reliability of long-term storage of information, simple combination of disks in RAID-6 is not enough. It is necessary to create backup copies of information, their number being determined by reliability indices specified in design of information repository.

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