Chernyshov Aleksandr Viktorovich, Candidate of engineering sciences, associate professor, sub-department of applied mathematics, computer science and engineering, Mytischi Branch of Bauman Moscow State Technical University (National Research University) (1 1st Institutskaya street, Mytischi-5, Moscow region, Russia), E-mail: email@example.com
Background. One of the tasks of designing long-term electronic storage is to minimize the number of data carriers while achieving the maximum possible reliability of information storage. When using optical disks as media, this problem can be solved by combining the media into RAID structures. However, for archives that do not use expensive robotic libraries, there is a problem of rapid access to stored information. The problem can be solved by combining media in hybrid structures, where along with RAID arrays; information is also stored on single media. The aim of the study is to build a mathematical model of the reliability of information storage on optical disks combined in hybrid structures (named in the paper as G5, G6, G15, G16), and determine the most profitable structure using this model.
Materials and methods. The model is based on well-known methods for evaluating the reliability of RAID arrays developed for hard disks, which were supplemented with expressions to account for the reliability of storing information on groups of single disks. The initial data for the model is considered: the total volume of archive storage, the capacity of a single optical disk, the probability of failure of the optical disk during storage between integrity checks, the conditional number of disks with information in the RAID array, and the number of spare copies being made.
Results. A model is constructed and simulations are performed for various values of the capacity of the electronic archive. For comparison, we also performed simulations for RAID-based archives of the most common types (5, 6, 15, 16), as well as for an archive based on single disks with spare copies. It is confirmed that although hybrid structures are less reliable than "pure" RAID, they are significantly superior to archives on single disks.
Conclusions. According to the results of the study, we can definitely recommend the G16 structure for creating archives on optical disks combined in hybrid structures.
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