Replica caching scheme according to status of neighboring nodes in optical grid networks

This paper proposes a replica caching scheme according to status of neighboring nodes in optical grid networks. In optical grid networks, data files for job execution are replicated at multiple servers in order to distribute loads. Clients download replicas via lightpaths and store those replicas as necessary. The blocking probability of lightpath establishments depends on location of replica files. The case that a replica of a data file is stored in a client is ideal because blocking does not occur. However, the storage size of the client is limited. In order to efficiently use storage space of clients, the proposed scheme focuses on the fact that lightpath establishments are rarely blocked if data files are stored at neighboring nodes. In the proposed scheme, clients preferentially store data files which are not stored at neighboring nodes. By doing so, each client and its neighboring nodes store replicas of more different data files. As a result, when a client downloads a data file, at least one replica of the data file tends to be stored at the client or neighboring nodes. Through simulation experiments, we show that the proposed scheme improves the blocking probability of lightpath establishments efficiently.