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Database clean require IM services to be temporarily stopped (eg use PASGUI.EXE).
Read the IM Configuration User's Guide for more detail.
Despite stopping PAS, Basic History will continue to deliver short term trends.
Otherwise an IM is not involved too much into the plant operation unless used as a Batch Historian and/or gateway for Smart Client. The Event Collector of diagnostic messages from IM may trigger temporary orange indication in alarm lists. This is expected and can be prevented by unticking "Significant Alarm Source" option in the Alarm Collection Definition. IM is not a significant source of alarms, your PLC's OPC servers are.
A database clean is considered "normal maintenance" procedures, still I recommend using IM Backup to create backups of the trends and events at some suitable interval.
- Thank you for your help, Master🙏