WinCC RedundancyControl - Error Watchdog timeout causes failover

One server of a WinCC (V7.4 SP1 Update 23) Redundant Server pair goes in FAULT state now and then.

In the log files it indicates each time one of the watchdog timeouts below: 

kustomcity

Hello,
 

Yes, this could be any of or a combination of the causes you mentioned like scripts and pdls.  I normally look at the WinCC\Diagnose directory and the 
WinCC_SStart_xx.log and WinCC_Sys_xx.log files. These will sometimes have clues to scripting overflows or even specific script errors. With a random error, it is hard to know an exact cause but  HealthCheck error can be a combination of causes.. However, eliminating as many errors(illegal tag issues, faulty archive storage paths, etc. ) from the logs as possible is the best start. More improvements were made to WinCC overall performance in versions such as 7.5 and 8.0. That means it was able to handle these types of issues when they might occur.  Also, check the Windows Event Viewer to see if there were specific error and warnings on the time and date of the Health Check issue. I also use the "Process Explorer" tool for Sys Internals Microsoft Suite to help monitor processes more specifically and can show memory growth patterns. 

 

Thanks,

Steve

It happens now and then without any clue in WinCCDiagnose-logs.

When this redundant server goes into the FAULT-redundant state, WinCC Runtime on this server keeps working without a problem but the other server is off course switched to Master including all clients.

I can't find any reason why a script or pdl in this project can cause a redundant failure.

WinCC_SStart_xx.log: contains only logged lines from starting a project until entering running state.

WinCC_Sys_xx.log: no a single indication around the outage timestamp

I guess path "C:\Program Files (x86)\Common Files\Siemens\ace\bin\Diagnosis" on both servers contains all the real logs about redundancy but understanding the logic in there?