General Fractional Repetition Codes for Distributed Storage Systems

In order to provide fault-tolerance and guarantee reliability, data redundancy should be introduced in distributed storage systems. The emerging coding techniques for storage such as fractional repetition codes, provide the required redundancy more efficiently than the conventional replication scheme. In this letter, we extend the construction of fractional repetition codes and present a new coding scheme, termed general fractional repetition codes. The proposed codes can be applied to storage systems in which the storage capacities of nodes may be different. Based on a combinatorial structure known as group divisible design, the new code construction is available for a large set of parameters. The performance of the proposed codes is evaluated by a metric called node repair alternativity, which measures the number of different subsets of nodes that enable the repair of a specific failed node.