Replica Selection and Downloading based on Wavelength Availability in λ-grid Networks

Abstract

This paper proposes a replica selection and downloading scheme in λ-grid networks. In λ-grid networks, in order to distribute loads and achieve high performance computing, a large amount of data is replicated on storage servers as files, and clients download these replicas. To download replicas efficiently, an appropriate replica selection scheme which avoids wavelength contention is required because λ-grid networks employ optical networking. The proposed scheme provides Replica Selection based on Wavelength Availability (RSWA). According to RSWA, a replica is selected based on wavelength availability collected by backward reservation. Furthermore, to suppress blocking probability of download attempts and improve downloading time of replicas, the proposed scheme introduces multiwavelength downloading, which determines the number of wavelengths used for each downloading based on wavelength availability. Through simulation experiments, we show that the proposed scheme can reduce blocking probability of download attempts and improve average downloading time efficiently.