Abstract: Owing to the high availability and space-efficiency of erasure codes, they have become the de facto standard to provide data durability in large scale distributed storage systems. The update intensive workloads of erasure codes lead to a large amount of data transmission and I/O cost. As a result, it becomes a major challenge to reduce the amount of data transmission and optimize the use of existing network resources so that the update efficiency of the erasure codes could be improved. However, very little research has been done to optimize the update efficiency of the erasure codes under multiple QoS(quality of service) metrics. In this paper, the proposed update scheme, the ACOUS (ant colony optimization algorithm based multiple data nodes update scheme) employs a two-stage rendezvous data update procedure to optimize the multiple data nodes updates. Specifically, the two-stage rendezvous data update procedure performs the data delta collection and the parity delta distribution efficiently, based on a multi-objective update tree which is built by the MACOU(multi-objective ant colony optimization update routing algorithm). Under typical data center network topologies, extensive experimental results show that, compared with the traditional TA-Update scheme, the proposed scheme is able to achieve 26% to 37% reduction of update delay with convergence guarantee at the cost of negligible computation overhead.

Key words: distributed storage system, data update, erasure codes, ant colony optimization, update delay