Operator Station Archive Reconciliation in Master/Master Failover
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Solution Overview
Problem
In control systems with redundancy for technical installations, master/master scenarios due to communication failures lead to independent data archiving by both operator station servers, resulting in potentially incorrect or incomplete data, and require significant memory for duplicate archiving and subsequent cleaning to maintain historical integrity.
Innovation Solution
The control system continuously records the health state and master/slave function of each operator station server at specified time intervals, synchronizing data archives to prioritize data from the server with the best health state, ensuring that only the highest quality data is retained during and after master/master scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If both operator station servers independently archive data during master/master scenarios, then data availability is maintained, but data quality and historical integrity deteriorate due to potential duplicates and inconsistencies
Solution Approach 1:
The system performs preliminary archiving of data in both servers during master/master scenarios, then subsequently reconciles the archives by comparing health states and selectively overwriting entries. This allows data to be captured immediately while quality issues are resolved in a second step, preventing loss of valuable data during transitions.
Solution Approach 2:
The system changes the parameter of data selection by using health state values as a criterion for determining which server's data to retain. During reconciliation, the server with the better health state has its data prioritized, transforming the archiving process from simple duplication to quality-based selection.
2Reliability
If both operator station servers archive data independently, then redundancy is achieved, but memory requirements increase due to duplicate archiving
Solution Approach 1:
The system discards duplicate or lower-quality data during reconciliation by overwriting archive entries with data from the server having the better health state. This selective discarding reduces memory consumption while preserving redundancy benefits, as only necessary duplicate data is maintained.
3Productivity
If both operator station servers archive data independently, then continuous recording is maintained, but subsequent cleaning processes become complex and time-consuming
Solution Approach 1:
The system uses health state information as feedback to guide the reconciliation process. By continuously monitoring and comparing health states between servers, the system automatically determines which data to retain without requiring complex manual cleaning processes, significantly reducing time investment.
4Reliability
If the slave inherits master function immediately upon failure, then availability is improved, but data correctness may deteriorate if the master was unhealthy
Solution Approach 1:
The system performs preliminary data capture in both servers during master/slave transitions, then subsequently reconciles the data by comparing health states. This ensures that even if the slave inherits master function immediately, the final archived data reflects the highest quality source, preventing propagation of unhealthy data.
Data Source
AI summary
A control system for a process or manufacturing installation includes a first and second operator station servers, wherein one operator station server operates as master and the other of operates as slave that inherits master functionality when the master fails, respective data archives are implemented on the first and second operator station servers, the first and second operator station servers each receive data of the technical installation and record it in the respective data archive, and the first and second operator station servers each ascertain a respective health state, where the first and second operator station servers continuously record in the respective data archive, at specified time intervals, which health state the respective operator station server has when receiving and recording the data of the technical installation, and whether the respective operator station server acts as master or as slave in the respective time interval.