IM: Force Synchronization on running system
Hi Stefan. Our customer got a service event stating that there are a number of IM logs out of sync. I have 2 questions:
1) Is Force Synchronization the way to resolve this issue?
2) Is it safe to run Force Synchronization on a running production system - or are there some steps to be taken first?
Thanks in advance,
Voted best answer
Yes, I believe forced sync is the way out.
As the tool says, the logs affected by this forcing need to be temporarily stopped and restarted during the correction. There might be additional data entries written to the log as an effect of this.
Apart from some potential extra data points, the effect is temporarily loss of access to this log. For operators, it should not be such a big issue. Primary log running in Basic History will remain available all the time and operator should be able to retry calling the trend in case the IM log was the only viable choice when retrieving data (e.g. out of scope for time interval of interest, or hard coded log selection)
A common cause for out of sync logs are if any of the presentation attributes (min, max, no of dec or engineering unit) has changed. For unknown reason, IM need to force such sync into its config. Really, I believe lagging presentation attributes in IM only bothers if IM's built-in presentation tools are used (Desktop Trends, Display Services or raw SQL access towards IM DB).
Íf you are interested, there should be some thread on AKS explaining on how to turn on the check sync log; this log will tell why sync is required. As said, its often only a presentation attribute that has changed in the PLC.