Data loss versus data availability: Key differences and implications
- Last UpdatedSep 27, 2025
- 2 minute read
It is important to understand the difference between data loss and data availability. Data loss is what happens if a PI interface goes down without another failover interface picking up data collection or not having history recovery functionality available. The data is often lost forever. All customers want to avoid data loss.
When data is unavailable, PI data cannot be accessed by displays, reports, or applications at that moment, but it will become available later. For example, if a non-high-availability Data Archive server goes down, PI Vision cannot display the data immediately. However, PI Interfaces continue collecting and buffering data to forward to the Data Archive once it’s back online, ensuring no data is lost. Lack of data availability means that PI data is not available for consumption by a display, report, or application at that time (but will be available for consumption at a later time).
The following table summarizes some of the differences between data loss and data availability.
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Concerns |
Data loss |
Data availability |
|---|---|---|
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Who is concerned? |
Everyone is concerned about data loss. |
Many are concerned about data availability. |
|
Drivers for concern |
No one ever wants to lose data. Loss of data has potential regulatory issues, and it may impact the perceived integrity of a controlled or regulated system. |
Availability concerns are driven by your use of the data and how much it is integrated into your business processes. |
|
Questions to ask |
If the PI Interface, a Data Archive server, or other AVEVA™ PI System™ component goes down, will I lose data? |
If the Data Archive server goes down, can my end users wait [4 hours] to see their data? What is the business impact of this? |
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Risk mitigation technologies |
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