VGrADS: enabling e-Science workflows on grids and clouds with fault tolerance. - Lavanya Ramakrishnan; Charles Koelbel; Yang-Suk Kee; Richard Wolski; Daniel Nurmi; Dennis Gannon; Graziano Obertelli; Asim YarKhan; Anirban Mandal; T. Mark Huang; Kiran Thyagaraja; Dmitrii Zagorodnov (SC, 2009)