Causality considerations in distributed, persistent operating systems

In this paper we describe a new persistent distributed operating system. The Grasshopper system is designed to allow flexibility in the way in which persistence is provided. A key element of this flexibility is concerned with issues of global consistency. The Grasshopper kernels cooperate with user level entities in order to maintain and find globally consistent states using vector time. Further flexibility is provided by allowing the kernels to implement either eager or lazy consistency policies