  Elasticity is offered by cloud service providers to exploit under-utilized
computing resources. The low-cost elastic nodes can leave and join any time
during the computation cycle. The possibility of elastic events occurring
together with the problem of slow nodes, referred to as stragglers, increases
the uncertainty of the system, leading to computation delay. Recent results
have shown that coded computing can be used to reduce the negative effect of
elasticity and stragglers. In this paper, we propose two hierarchical coded
elastic computing schemes that can further speed up the system by exploiting
stragglers and effectively allocating tasks among available nodes. In our
simulations, our scheme realizes 45% improvement in average finishing time
compared to the state-of-the-art coded elastic computing scheme.
