Hi,

So you did a OS download change to both servers and after that you executed a full download to only one server? 

If so, please execute a full download to the other server as well. After that, the servers should be syncing.

Hi,

It could be that the master OS has a problem, but does not switch over. The system looks ok, but it isn't. What you can do is to check the @RM_Master tag on both OS in tag management of WinCC. You may have to unhide the column: Value in order to show the actual values. The tag is located in the internal tags section. Check which one has value 1 which mean it's set as master.

Then try to deactivate that OS server so the standby server can take over. You could get a message indicating switchover will lead to redundancy loss. In this case only proceed when it is allowed, since operators will have no visualization until one server is booted in runtime again.