Distributed System

Asem Bani Salameh · Post by **Asem Bani Salameh** » Mon Aug 13, 2018 4:31 pm

Good day,

We are facing an issue with Distributed System architecture. In order to explain , in our case there will be multiple servers and one master server that is going to collect data from all lower level servers as shown in the attached image.

All workstations to be connected to the Master server only ;such that the operators are capable to see the whole distributed projects together wherever they are.
In such topology the smaller servers are used to collect data , data conversion, archiving ,etc.... but not for the UI connections.

So here it comes up the concern of the maximmum number of dpconnects and control functions that could be handled by the master server Event and distribution managers' as it will run all workstation's UI.

Regards

leoknipp · Post by **leoknipp** » Fri Aug 17, 2018 10:41 am

The picture was missing therefore we cannot how the architecture looks like.

Are the server systems redundant or single servers?
What amount of data (value changes / second) do you expect for the servers collecting data?
How many systems will connect to the master system?
How many UIs will be started for the master server?

Data is only transmitted via the distribution manager if there is a connect for it or if some requested data, e.g. doing a dpGet(), dpGetPeriod(), .....
As long as no one is connected to data for another system there is no data exchange.

Best Regards
Leopold Knipp
Senior Support Specialist

Asem Bani Salameh · Post by **Asem Bani Salameh** » Sun Aug 19, 2018 2:28 pm

1) The project will contain one master Redundant server and 23 redundant slave servers
2) We are going to have Redundancy between servers (23*2=46)
3) The master server is going to connect with 150 UI sessions, many of them includes 5 screens (MultiMonitor)
4) Oracle enterprise to be installed on each server and there exist master Oracle server
5) Master server some hardware specs: Base: PowerEdge R740XD , Processor : Intel Xeon Gold 6126 2.6 G ,19.25 M cache ,turbo , Memory DIMM :32 GB, 2666MT/s , Hard drive :600 GB 15 K RPM SAS .
6) Slave server specs: Base: PowerEdge R440 , Processor : Intel Xeon Silver 4112 2.6 G ,8.25 M cache ,turbo .Memory DIMM :16 GB, 2666MT/s , Hard drive :300 GB 15 K RPM SAS .

7) Calculations of number of dpconnects per one UI :

-Network Panels (Big panels ) contain around 400 value display and animation each one is using separate dpconnect script(( *? Is it better to combine more than one variable in the same dpconnect (listen to 20 tags with the same dpconnect or it doesn’t matter))

-Normal panels contain around 100 dpconnect

So from these information it’s possible to calculate the number of dpconnects that are handled by Master server:
150 Ui* 4 screens *300 =180,000 that would be the worst case scenario.

Please advise if this configuration will work on wincc oa

leoknipp · Post by **leoknipp** » Mon Aug 20, 2018 1:24 pm

Thanks for the information.
In your answer one important part is missing.
What amount of data (value changes / second) do you expect for the servers collecting data?

As a first test you could setup and configure your redundant master server with a data model similar to the plant system. When the server system is running you can start up to 150 UI-managers to see if your server is capable of handling such a high number of UI-managers.

Best Regards
Leopold Knipp
Senior Support Specialist

Asem Bani Salameh · Post by **Asem Bani Salameh** » Sun Aug 26, 2018 8:00 am

Good day all ,

Thanks for the answer Leo , and sorry for the late reply.

Possibly we are going to have 750,000-1,000,000 value changes per second handled by multiple protocols and drivers.Is there another possible solution rather than making the previously mentioned ; test as at this stage in the project i doubt that this would be possible.

Regards

leoknipp · Post by **leoknipp** » Mon Aug 27, 2018 9:37 am

If you expect 750.000 value changes / second and you have 23 sub systems every system has to handle a load of 33.000 values changes / second, if the load is similar in every system.
33.000 value changes / second as constant load is a very high value.

Is the number of 33.000 value changes / second the load produced by the PLC or the load which needs to be processed in the WinCC OA system?
Are you sure that every system will have such a high constant load?

Normally the number of value changes / second in the PLC is not the same as the number of changes which needs to be processed in the system, e.g. the load is reduced by an old/new comparison or smoothing in the driver.

Maybe it would be better to discuss your project configuration and the requirements directly. Therefore please get in contact with your responsible WinCC OA sales contact to clarify how to proceed in this case.

Best Regards
Leopold Knipp
Senior Support Specialist

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