¨INRIA, *UIUC, °ORNL

Over the past few years resilience has became a major issue for HPC systems, in particular in the perspective of large Petascale systems and future Exascale ones. These systems will typically gather from half a million to several millions of CPU cores running up to a billion of threads. From the current knowledge and observations of existing large systems, it is anticipated that Exascale systems will experience various kind of faults many times per day. It is also anticipated that the current approach for resilience, which relies on automatic or application level checkpoint-restart, will not work because the time for checkpointing and restarting will exceed the mean time to failure of a full system. This set of projections leaves the community of fault tolerance for HPC systems with a difficult challenge: finding new approaches, possibility radically disruptive, to run applications until their normal termination despite the essentially unstable nature of Exascale systems. Yet, the community has only five to six years to solve the problem. This white paper synthesizes the motivations, observations and research issues considered as determinant of several complementary experts of HPC in applications, programming model, distributed system and system management