Lambda scheduling algorithm for file transfers on high-speed optical circuits

Scheduling resources on Grids is a well-known problem. The extension of Grids, to LambdaGrids requires scheduling of lambdas, i.e., end-to-end high-speed circuits. In this paper we propose an heuristic for the scheduling of lambdas specifically for file transfers, given that many eScience applications require high-throughput transfers of large files. We call this heuristic varying-bandwidth list scheduling (VBLS) because the scheduler returns a time-range-capacity (TRC) allocation vector with varying banchwidth levels assigned for different time ranges within the duration of a transfer. The advantage of VBLS over a fixed-bandwidth allocation scheme is that it allows the scheduler to backfill any holes left in resource allocations. Such a scheme is enabled by end host applications specifying the file size in their transfer requests. To characterize VBLS, we used analytical models and ran simulations. Our results show that VBLS performance is close to packet-switching performance, which means that file transfers can take advantage of bandwidth that becomes available subsequent to the start of transfers, a critical drawback of typical fixed-bandwidth allocation schemes in circuit-switched networks.