Importance

Loading Importance Indicators...

Abstract

A fault tolerant computer system employing primary tasks and corresponding backup tasks. The system operates to provide fault tolerant operation even where uncontrolled external events may occur whose time of occurrence may affect task performance. For this purpose, external event data is stored for each external event occurring during performance of a primary task which indicates the event type and the relationship between the occurrence of the external event and the occurrence of a predetermined primary task event, such as a memory access operation. This external event data is sent to each respective backup task along with messages transmitted to the respective primary task. In the event a primary task fails, the backup task will replay the failed primary task by processing these transmitted messages while using the transmitted external event data to redeliver each external signal to the backup task at an appropriate time which will assure that the backup task properly recovers the primary task.

Loading the Abstract Image...

First Claim