Preferred Server Settings - Siemens SIMATIC PCS 7 Operation And Maintenance

Installing updates and service packs
3.3 Checking plant status
You should therefore check if a server is a standard server before deactivating runtime on it.
Deactivation of process mode on the OS server must be timed in such a way that the
functionality it provides will not be missed.
Note
When a redundant OS server is used, the functionality of the standard server will be
maintained only if one computer of the OS server pair is deactivated.
If no standard server is configured for alarms of an OS client, then the OS client will not
generate any operator messages.
3.3.6

Preferred server settings

Function of the preferred server in process mode
If redundant OS servers are used, then the OS client will interconnect with the OS server
which has been configured as the preferred server. If the preferred server fails, the OS client
switches to its partner server. When the failed preferred server returns, the OS client will
switch back to this OS server.
We recommend configuring the preferred server for the OS client on the ES and then loading
the OS client. Because the preferred server can also be configured on the OS client via the
WinCC Explorer, you should check the preferred server directly on the OS client.
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Compendium Part D - Operation and Maintenance (V9.0)
Operating Manual, 02/2018, A5E43228948-AA