A fault tolerant consensus generation and communication system and method is described. Each processing node in the system receives a plurality of measurements from a sensor, calculates a consolidated value for the received plurality of measurements, transmits the consolidated value to other processing nodes, receives consolidated values from the other processing nodes, calculates a consensus value based on the calculated consolidated value and the received one or more consolidated values, transmits the calculated consensus value to the other processing nodes, receives consensus values from the other processing nodes, generates a consensus message based on the calculated consensus value, the received one or more consensus values, and a predefined criterion, and, in a case where the consensus message is not present in a consensus queue, adds the consensus message to the consensus queue.

A networked database management system (DBMS) is disclosed. In particular, the disclosed DBMS includes a plurality of nodes, one of which is elected as a designated leader. The designated leader is elected using a consensus algorithm, such as tabulated random votes, RAFT or PAXOS. The designated leader is responsible for managing open coding lines, and determining when to close an open coding line.

The present invention provides a data processing device that includes a memory and includes a first CPU and a second CPU, each having an instruction processing section to process an instruction, a cache to store part of data of the memory, an error detection section to detect an error in the data stored in the cache, and an error correction section to correct the data stored in the cache on the basis of the data stored in the cache and an error notification and output corrected data to the instruction processing section, wherein the error correction section of the first CPU receives, as input, the data stored in the cache of the first CPU, the error notification of the first CPU, the data stored in the cache of the second CPU, and the second error notification, and if the error notification of the first CPU is an error and the error notification of the second CPU is not an error, outputs the data stored in the cache of the second CPU to the instruction processing section of the first CPU, and in other cases, outputs the data stored in the cache of the first CPU to the instruction processing section of the first CPU.

Described in detail herein is a system for determining the validity of a transaction in a distributed network environment. The system includes a plurality of peer servers. The system elects a set of peer leaders from the plurality of peer servers. The set of peer leaders broadcast a first set of indices associated with a first subset of transactions, received from the plurality of peer servers, to one or more of the plurality of peer servers. The set of elected peer leaders execute a first instance of a binary agreement protocol based at least in part on a second subset of indices associated with a second subset of the transactions. The set of elected peer leaders output a consensus vector comprising one or more of the transactions.

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for performing view change. One of the methods is to be implemented on a blockchain and performed by a first node of N nodes in a view change protocol. The method includes: multicasting a view change message to at least some of the N nodes; obtaining, respectively from at least Q second nodes of the N nodes, at least Q echo messages each comprising: a consistent current view known to the second node indicating a primary node designated among the N nodes, and a consistent current sequence number known to the second node, the current sequence number associated with a latest transaction or a latest block, the current sequence number is larger than a first sequence number known to the first node; and responsive to obtaining the at least Q echo messages, ending the view change protocol.

In one embodiment, a multiplex control device includes three or more control modules to execute same operations for same input signals, and a majority decision module to output an output signal that matches majority of output signals outputted by the control modules. Each control module includes an input module to convert an input signal into an input value, a first determination module to obtain input values from input modules of respective control modules to determine whether majority of input values among the obtained input values match, an operation executing module to execute an operation using the matched input value to generate an output value, a second determination module to obtain output values from operation executing modules of respective control modules to determine whether majority of output values among the obtained output values match, and an output module to convert the matched output value to generate an output signal.

A dual redundant computer safety relay box system includes first and second fail-safe computing systems (FSCs) individually mounted to first and second printed circuit boards. Each FSC includes two computing modules (CPUs) designated as a first CPU and a second CPU. The first and second FSC's are both connected to a safety relay box. The printed circuit boards are isolable from each other permitting maintenance on one of the printed circuit boards while operation of the FSC of the other printed circuit board is maintained. In each FSC a health signal generated from the first and second printed circuit boards of the first and second CPUs defines a multi-level dynamic pulse signal. Presence of the dynamic pulse signal produces an output identified as each of a first and a second healthy indication signal from each of the CPUs of one of the first or second FSCs.

A method of arbitrating conflicting outputs in a redundant control system. Execution data of a task executed by each controller in the redundant control system is recorded. The execution data includes an initial timestamp of each execution stream, identification of critical functions in each execution stream, and parameter values used by the critical functions. A path executed by each controller is identified based only on the critical functions executed for each execution stream. The recorded execution data of each executed path is applied to an arbitration module. An output result from one of the respective controllers selecting, by an arbitration module, based on the recorded execution data of each executed path. The output result of the selected controller is communicated to a next module for further processing.

A processor-implemented method, for continuing operation of a quorum based system is provided. The method detects a loss of quorum. A plurality of speculative configurations is created, whereby each speculative configuration is isolated from other speculative configurations in the quorum based system. Each speculative configuration continues to order requests during the creation of speculative configurations. The method selects and starts one of the plurality of speculative configurations as a new operational configuration. Ordered requests continue to the new operational configuration. The original configuration of the quorum based system is restarted in response to the plurality of speculative configurations not being isolated.

A computer-implemented method may comprise executing, by a first plurality of replicated state machines, a sequence of ordered agreements to make mutations to a data stored in a first data storage service of a first type and executing, by a second plurality of replicated state machines, the sequence of ordered agreements to make mutations to the data stored in a second data storage service of a second type. First metadata of the mutated data stored in the first data storage service may then be received and stored, as may second metadata of the mutated data stored in the second data storage service. A comparison of the stored first and second metadata may then be carried out when the data stored in the first data storage service that corresponds to the first metadata and the data stored in the second data storage service that corresponds to the second metadata have been determined to have settled according to the predetermined one of the sequence of ordered agreements. A selected action may then be carried out depending upon a result of the comparison.