OPC Data Archiving: Storage Volume, Performance Impact, and Compression

OPC Expert’s archiving capability is limited in practice by the available disk space and database capacity of the chosen storage target rather than by an internal ceiling within the software itself. Performance impact on the host PC is intentionally minimized through event-based data capture, which records values only when they change rather than on a fixed polling interval. This approach reduces both CPU load and storage consumption significantly compared to time-based archiving strategies.

How Event-Based Capture Reduces Storage and Load

Rather than writing a value at every scan interval regardless of whether anything has changed, OPC Expert records data on exception, meaning a new record is written only when a value changes beyond a configured deadband or when a defined update rate elapses. This is the same principle used by industrial historians, and it dramatically reduces the number of records written over time for slowly changing or stable process variables. The result is a smaller archive and lower write activity on the host machine, which is particularly important when archiving a large number of tags simultaneously.

Storage Formats and Practical Capacity

OPC Expert archives data to CSV files and relational databases including Microsoft SQL, MySQL, and SQLite, as well as cloud targets such as Microsoft Azure and Amazon AWS. The practical storage limit depends on the format chosen and the infrastructure it runs on. CSV archives grow indefinitely and are bounded only by disk space. SQL-based archives can be managed using standard database maintenance tasks such as scheduled purges, table partitioning, or data retention policies. OPC Expert does not impose a tag count ceiling on archiving, and the webinar demonstrated archiving multiple data sources simultaneously with no observable performance degradation on the host machine.

FIFO Behavior and Compression

OPC Expert does not implement a native FIFO buffer in the way that some dedicated historians manage rolling data windows, nor does it apply proprietary compression algorithms such as those found in PI or other enterprise historians. The event-based capture model provides effective data reduction without requiring a separate compression layer, because only meaningful changes are stored. If a FIFO or rolling retention window is required, this is best managed at the database level using the storage format of your choice rather than within OPC Expert itself.

Relevant Tools

Archive OPC Data is the OPC Expert module that captures and stores real-time OPC data using event-based archiving to CSV, SQL, and cloud targets. It runs as a Windows service, requires no installation, and includes a store-and-forward mechanism that prevents data loss during network disruptions.

OPC Trend Software is the OPC Expert module for visualizing and analyzing archived data. It connects to OPC Expert’s built-in historian or to third-party historians via OPC HDA and OPC UA HA, delivering real-time and historical trend views including on mobile devices.

Summary

OPC Expert’s archiving module is bounded by available storage infrastructure rather than internal software limits. Event-based capture reduces PC load and storage requirements by recording data only on meaningful change. There is no native FIFO mechanism, but retention management can be handled at the database level in whichever storage format is selected.