Load sharing in hypercube-connected multicomputers in the presence of node failures

The paper addresses two important issues associated with load sharing (LS) in hypercube-connected multicomputers: (1) ordering fault-free nodes as preferred receivers of "overflow" tasks for each overloaded node and (2) developing an LS mechanism to handle node failures. Nodes are arranged into preferred lists of receivers of overflow tasks in such a way that each node will be selected as the kth preferred node of one and only one other node. Such lists are proven to allow the overflow tasks to be evenly distributed throughout the entire system. However, the occurrence of node failures will destroy the original structure of a preferred list if the failed nodes are simply dropped from the list, thus forcing some nodes to be selected as the kth preferred node of more than one other node. The authors propose three algorithms to modify the preferred list such that its original features can be retained regardless of the number of faulty nodes in the system. It is shown that the number of adjustments or the communication overhead of these algorithms is minimal. Using the modified preferred lists, they also proposed a simple mechanism to tolerate node failures. Each node is equipped with a backup queue which stores and updates the information on the tasks arriving/completing at its most preferred node.