Architectural support for designing fault-tolerant open distributedsystems

An overview of the main techniques for designing fault-tolerant software and hardware systems is provided. The important features of the building blocks (computers, memories, buses, etc.) that can support an efficient implementation of fault-tolerant open distributed systems (FTODSs) are identified. Taking into account the features of these building blocks, an organization for FTODS is proposed. A distributed voting algorithm and a two-level hierarchy for permanent memory are key elements in this scheme. The algorithms needed for transferring files and synchronizing the concurrent activities of the computing modules and for recovery-are ISO standard protocols. Low-level voting and recovery algorithms that can run as a layer of software above the operating system make the open distributed system an attractive environment for applying fault-tolerant techniques