Providing data transfer with QoS as agreement-based service

Over the last decade, grids have become a successful tool for providing distributed environments for secure and coordinated execution of applications. The successful deployment of many realistic applications in such environments on a large scale has motivated their use in experimental science [L. C. Pearlman et al., (2004), K. Keahey et al. (2004)] where grid-based computations are used to assist in ongoing experiments. In such scenarios, quality of service (QoS) guarantees on execution as well as data transfer is desirable. The recently proposed WS-Agreement model [K. Czajkowski et al. K. Keahey et al. (2004)] provides an infrastructure within which such quality of service can be negotiated and obtained. We have designed and implemented a data transfer service that exposes an interface based on this model and defines agreements which guarantee that, within a certain confidence level, file transfer can be completed under a specified time. The data transfer service accepts a client´s request for data transfer and makes an agreement with the client based on QoS metrics (such as the transfer time and confidence level with which the service can be provided). In our approach we use prediction as a base for formulating an agreement with the client, and we combine prediction and rate limiting to adoptively ensure that the agreement is met.