Client-Server Connections; Archive Synchronization Of The Redundant Os Server After A Hot Restart Of The Standby Server - Siemens SIMATIC PCS 7 Operation And Maintenance

Installing updates and service packs
3.3 Checking plant status
3.3.8

Client-server connections

When an OS server is deactivated, not all OS clients should be connected to another OS
server at once, because the plant is temporarily inoperable in this case. Therefore, you need
to determine the OS server to which the OS clients are currently connected. As a general
rule, you should distribute the OS clients evenly across the redundant OS servers. You
achieve this goal via the preferred server configuration.
Checking the @RM_SERVER_NAME internal OS variable
The @RM_SERVER_NAME internal OS server variable contains the name of the OS server
that provides the process picture to the OS client. This variable can be be visualized in the
process picture, for example, in a text field. When the screen appears you can see from the
text box to which OS server the OS client is currently connected.
Note
You can find more information in FAQ "On the WinCC client, how can you determine which
server it is connected to?" (https://support.industry.siemens.com/cs/ww/en/view/11768430).
3.3.9 Archive synchronization of the redundant OS server after a hot restart of the
standby server
Scenario
Server A is the master server and server B is the standby server. Maintenance work needs
to be performed on the redundant OS server. No preferred server is configured for OS
clients; the OS clients are therefore connected to the master server.
To avoid an unnecessary redundancy switchover of the OS clients, the standby server will
be deactivated first in this case. Once the maintenance work is complete, server B will be
restarted.
A time window of two hours is required for the maintenance work. Within this time window,
the TagLogging and AlarmLogging values have only been archived by server A.
Before you deactivate server A for the required maintenance work, you need to ensure that
archive synchronization has been completed in full.
Note
If server A is deactivated before the archive synchronization is complete, data loss can
occur.
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Compendium Part D - Operation and Maintenance (V9.0)
Operating Manual, 02/2018, A5E43228948-AA