Abstract: Updating of control code is accomplished in multiple nodes of a computing system while the computing system remains in operation. Each node includes a processor, memory, a first version of a control code unit and an engineering change level indication for the control code unit. The method comprises the steps of: installing a revised version of the control code unit with converter code modules in a first node, the converter code modules enabling and performing first and second interface functions during communications between the first node and other nodes in the system. The first node is then operated to perform a function which requires communication with other nodes, the converter code module in the first node initially determining an engineering change level value stored in another node and, if the engineering change level values in the nodes match, communicating with the other node through the first interface function.

Abstract: In a distributed file system having a plurality of file servers each associated with a plurality of workstations having cache memories, data locks granted by the file servers to the workstations have variable lock lifetimes that are selected based on system parameters. The parameters selected to determine lock lifetimes can be either statically determined, in which case system operating parameters such as read/write ratio for data objects are assumed, or can be dynamically determined, in which case real-time system operating parameters such as current read/write ratios are used to determine the appropriate lock lifetime.