Stopping LocalHistorian data updates

[OK_8738941]

KEPServerEXVer6.17
Local Historian (501-10,000 tags)

OPC Connectivity Suite

When analyzing the historical data from LocalHistorian-HDA,
we found that data updates were stopped for approximately 12 minutes around 00:58:17 on November 13, 2025.

No quality abnormalities (e.g., Bad) were found on the OPC DA side before or after the stopped period.
Is there anything we can learn from the Application Report that will help us identify the cause of the 12-minute stoppage in HDA data updates?

[pshashipreetham]

Hi, 

A 10–15 minute gap in Local Historian updates usually indicates that the historian service paused writing rather than an OPC data issue. Since OPC quality remained good, the interruption most likely occurred in the historian write pipeline or system resources.

A few things worth checking in the Application Report / Event Log around the timestamp (00:58:17):

1. Look for Local Historian buffer or write messages. If the database file was temporarily locked, busy, or undergoing maintenance (backup, antivirus scan, disk IO spike), the historian may pause writes until the operation completes.
2. Check for disk or storage warnings. Local Historian relies heavily on disk IO. If the disk queue or latency spikes, updates can temporarily stop and then resume once the write buffer clears.
3. Review any system tasks at that time (Windows scheduled tasks, backup jobs, antivirus scans). These are common causes of short historian pauses.
4. Verify the Local Historian queue/buffer settings and check whether the buffer temporarily filled. If the buffer reaches its limit, updates pause until the backlog is written.

If the gap only occurred once, it is usually related to system resource contention or a background task rather than Kepware itself. The Application Report around that timestamp should show messages indicating whether the historian paused due to buffering, disk access delays, or system resource constraints.

Thanks,