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— Presentation at EAIS2016 —
August 1, 2016
Photo 1 The panel of IIAI AAI 2016
The 5th International Congress on Advanced Applied Informatics (IIAI AAI2016) was held in Kumamoto, Japan, from July 10 to 13, 2016 (Photo 1). Many researchers from Japan and Asia discussed about information science in IIAI AAI. IIAI AAI2016 consists of 7 conferences, such as educational system and artificial intelligence not only computer architecture. In this year, there were 271 presentation including oral and poster. There are 23 presentations in the data science, 32 presentations in the artificial intelligence, and 54 presentations in the architecture; therefore, these research areas may have strong interests. I joined the 1st International Conference on Enterprise Architecture and Information Systems (EAIS2016) to propose "REC2: Restoration Method Using Combination of Replication and Erasure Coding".
After large-scale disaster, such as the Great East Japan Earthquake, information systems are disrupted by heavy shaking or tsunami. Sometimes, the information systems have important information to recover livelihood, such as medical records. Therefore, the disrupted information systems are needed to restore immediately after disasters. To restore the information system, data protection function is used. The function copies original data to one or more backup servers periodically. After disasters, the function restores the original data by using the backup data. It takes a long time to restore the original data.
To reduce the restoration time, generally, multiple backup servers are used, and a recovery server obtains the backup data in parallel. However, the more backup servers are used, the more amount of backup data. Thus, there is tradeoff between reducing restoration time and small amount of backup data. Moreover, when large-scale disasters occur, almost all the backup servers are temporarily stop, next the backup servers restart gradually. Therefore, immediately after large-scale disasters, a recovery server may not start to restore.
Fig. 1 Overview of a proposed method
To solve this tradeoff, we proposed a method which combines replication and erasure coding, called REC2. REC2 backs up and restore meta-data by replication and also backs up user-data by erasure coding (Fig. 1). From evaluation assuming the environments using 8 backup servers after the Great East Japan Earthquake, we confirmed that REC2 reduces the amount of backup data to 1/2 of ×8 replication, and the restoration time of REC2 only decreases 8.7% against ×8 replication, which is the fastest configuration.
This research is supported as "Research and Development on Highly-functional and Highly-available Information Storage Technology", sponsored by the Ministry of Education, Culture, Sports Science and Technology in Japan, and we are collaborating and researching with Tohoku University and Hitachi Solutions East Japan, Ltd.
(By KAMEI Hitoshi)