Research On Replica Selection Strategy In Data Grids

Data Grid architecture provides a large-scale, scalable infrastructure for the management of storage resources and data that are distributed across grid environments. Based on the requirement to data sharing and managing of data-intensive computing application, it provides the mechanisms for transparently remote accessing to heterogeneous data resources. Replica management is one of the critical parts in data grids. The replica created could reduce the network delay and bandwidth consumes when accessing to the data and improves load balance of network. It could also improve security, reliability and system tolerance of the data. Excellent replica management strategies are important to improve the QoS in data grids. Replica management strategies include replicas creation strategies, replicas selection strategies and replica location mechanism and so on. Replica selection strategies are an important tache in improving performance of the system. This paper investigates on replica selection strategies of replica management in data grids and the main work are as follows:(1) This paper improves and expands a replica selection strategy based on auction agreement and token technology by studying some replica selection strategies exist.(1)We import the concept of virtual and analysis the difference between virtual token-ring and token-ring.(2)We improve and extend a replica selection strategy based on auction agreement and virtual token-ring. This strategy selects a data replica from many replicas using auction protocols and token technology. Purchaser sent token to virtual token-ring. Bargainer receiving the token gives a price from it to the purchaser. Bargainer will decide whether modify the price on the token according to the price on the token. Purchaser will connect with bargainer who gives the lowest price and get the best replica according the information on the token.(3)This paper gives the arithmetic of purchaser and bargainer. (2) This paper puts forward a price calculating model after analyzing the situation of the node storing the replica, the factor of the network and their essentiality. This model could well weigh the communication cost between the purchaser and bargainer. We can also set different weight to emphasize particularly on different performance index which could satisfy the requirement of different purchasers. We also evaluate the affection that the performance index to the price.(3) This paper evaluates the performance of the replica selection strategy put forward. Comparing with the representative Robin selection strategy at present and set the performance index, we get two algorithmic delay models. We also emulate the delay performance of the two algorithmic models. We draw the conclusion that the strategy put forward provides an efficient search replica selection services.(4) This paper defines correlative class and agreement and also design and realized in allusion to the replica selection strategy based on auction protocol and virtual token-ring technology.