Top-end control system system architecture? Please explain?

rustydud

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Mar 2011
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Hey everyone
I'm new to a lot of the terminology on this drawing. This drawing shows the top-end control system architecture of a SCADA system.
I don't understand what the following terms:
"THIN CLIENT"
"ENGINEERING WORKSTATION"
"VIRTUAL SERVER HOST"
"SHARED STORAGE SERVER"

Ultimately I will need to spec the engineering workstation, the thin clients, the "MES", domain server, and virtual server host.
Can someone explain what the engineer is trying to show here? Why would each be needed in the system, what is their purpose?
Any helpful websites or videos that can explain these terms and all the nitty-gritty?
Thanks and Happy Friday.
 
Last edited:
My takes:

Thin client = dumb PC running some software via a server. Probably SCADA pages via the actual SCADA running in the Virtual Host Server.

Engineering workstation = PC with programming software for the Wonderware SCADA.

Virtual Server Host = Scada Server and/or database server (*) running in a virtual environment.
*: Probably not since there is a dedicated storage server.

Shared storage server = database server

There are many ways to interpret the diagram.
For example, is a thin client a front end for a full SCADA, or displaying pages from a SCADA with client/server functionality ?
And why is the SCADA running in a virtual environment but not the database server ?
Apart from initial guesses, I would be vary about provide advice based on guesses.
I would ask the engineer directly rather than trying and guessing via forum members that dont know your exact situation.
 
A thin client is simply a computer that depends upon another computer to handle much of it's task. This may mean that it runs as a simple terminal that rely's on a servers operating system or it may have a very simple operating system that does nothing more than fulfill its role as an HMI (for example).
 
Thin Client: http://en.wikipedia.org/wiki/Thin_client

ENGINEERING WORKSTATION = a workstation with the software needed to configure the system.

VIRTUAL SERVER HOST = A server that's purpose is to run multiple instances of virtual operating systems. Each operating system can be used to host different applications.

SHARED STORAGE SERVER = A network attached server that is mapped to many networked computers for the purpose of centralized data storage.
 
Thin Client: http://en.wikipedia.org/wiki/Thin_client

ENGINEERING WORKSTATION = a workstation with the software needed to configure the system.

VIRTUAL SERVER HOST = A server that's purpose is to run multiple instances of virtual operating systems. Each operating system can be used to host different applications.

SHARED STORAGE SERVER = A network attached server that is mapped to many networked computers for the purpose of centralized data storage.

+1. Awesome overview.

Typically one of the Virtual Servers will be a terminal server. The Thin Clients will remote into the terminal server. The actual application itself is running o the powerful Virtual Server, with a lot of resources. The Thin Client is typically a dumbed down simpler computer with lower resources, since it's primary purpose is to remote into a session on another computer (usually).

These are generalizations.
 
While simple on the drawing, the architecture is advanced considering the virtualization/HA element to it...

Pardon me on this blunt question, but if you aren't familiar with the terminology, how the heck are you going to spec the hardware??????
 
I should also add that there are eight(8) PLC RTU's. Each RTU will communicate to the Control Room via the 4G Cellular Communications Network. This network is indicated on the drawing I attached in the original post as "CELLULAR REMOTE NETWORK".

Thin Client:

VIRTUAL SERVER HOST = A server that's purpose is to run multiple instances of virtual operating systems. Each operating system can be used to host different applications.

Is that to say that a virtual server is a server that is "split up" into multiple servers, such that each server can run independently? Sort of like this?http://www.voyageurpc.com/products/scientific/images/virtual.gif

I don't understand why the engineer would want to go virtual in the first place?

While simple on the drawing, the architecture is advanced considering the virtualization/HA element to it...

Pardon me on this blunt question, but if you aren't familiar with the terminology, how the heck are you going to spec the hardware??????

I have a lot of support that won't be here till next week. Until then there are a few here that have graciously helped me with their knowledge. Thanks for everyone's comments.
 
Is that to say that a virtual server is a server that is "split up" into multiple servers, such that each server can run independently? Sort of like this?http://www.voyageurpc.com/products/scientific/images/virtual.gif

I don't understand why the engineer would want to go virtual in the first place?

Hello rustydud;
Before virtualization, each server required in your process had to be setup in its own physical support, that is a distinct hardware from Dell or HP or..., with its own server OS, power supply, 19" rack, HDDs and RAM, etc... If you had one server for database, one for the SCADA, one for the domain controller, one for the... that would start making a lot of computers and softwares.
By using virtualization you can take a single poowerfull machine, install virtual machine software and split the machines HDD and memory between a variety of logical servers, each with its own OS server license. Saves hardware and money over the long run.
If you want more detailed information, search Google for something like "Virtualization server", you will have enough hits to satisfy your curiosity, such as this link:
IBM Server virtualization
Hope this helps,
Daniel Chartier
 
Hello rustydud;
Before virtualization, each server required in your process had to be setup in its own physical support, that is a distinct hardware from Dell or HP or..., with its own server OS, power supply, 19" rack, HDDs and RAM, etc... If you had one server for database, one for the SCADA, one for the domain controller, one for the... that would start making a lot of computers and softwares.
By using virtualization you can take a single poowerfull machine, install virtual machine software and split the machines HDD and memory between a variety of logical servers, each with its own OS server license. Saves hardware and money over the long run.
If you want more detailed information, search Google for something like "Virtualization server", you will have enough hits to satisfy your curiosity, such as this link:
IBM Server virtualization
Hope this helps,
Daniel Chartier

VERY Helpful!
Also if anyone else has any links of videos, websites, etc that may be able to help my feeble mind...bring them on! Thanks!
 
Hello rustydud;
Before virtualization, each server required in your process had to be setup in its own physical support, that is a distinct hardware from Dell or HP or..., with its own server OS, power supply, 19" rack, HDDs and RAM, etc... If you had one server for database, one for the SCADA, one for the domain controller, one for the... that would start making a lot of computers and softwares.
By using virtualization you can take a single poowerfull machine, install virtual machine software and split the machines HDD and memory between a variety of logical servers, each with its own OS server license. Saves hardware and money over the long run.
If you want more detailed information, search Google for something like "Virtualization server", you will have enough hits to satisfy your curiosity, such as this link:
IBM Server virtualization
Hope this helps,
Daniel Chartier


Additionally, virtualization can help you extend the very short Windozz life cycle. Normally your top end computers need to be replaced every 5-7 years at a minimum. When upgrading it is normal to expect that you will need to upgrade the computer, operating system (due to driver support issues) and therefore also the control software that is running on the OS. By virtualizing, you can maintain the original operating system and control software versions. They will run inside the new operating system that comes with your new computer.

This is no small advantage and will keep down the overall cost of a computer replacement. The only problem is that not all control softwares support virtualization. That does not mean that it won't work, but it does mean that if you have any issues the control software OEM will not necessarily support you. To me, that is a small risk when you weigh it against the advantages.
 
Additionally, virtualization can help you extend the very short Windozz life cycle. Normally your top end computers need to be replaced every 5-7 years at a minimum. When upgrading it is normal to expect that you will need to upgrade the computer, operating system (due to driver support issues) and therefore also the control software that is running on the OS. By virtualizing, you can maintain the original operating system and control software versions. They will run inside the new operating system that comes with your new computer.

This is no small advantage and will keep down the overall cost of a computer replacement. The only problem is that not all control softwares support virtualization. That does not mean that it won't work, but it does mean that if you have any issues the control software OEM will not necessarily support you. To me, that is a small risk when you weigh it against the advantages.

Hydro Power Guy - your comment regarding the control softwares has been noted. That's a good tip, keep them coming! Thanks

It appears the data that is in the box on the bottom left hand corner of the drawing matches 1:1 the information that is contained in this document. This document outlines "ArchestrA System Platform in a Virtualized Environment Implementation Guide" http://www.vmware.com/files/pdf/techpaper/vmw-wonderware-ArchestrA-System-Platform.pdf

I'm thinking this is not a strange coincidence?
 
rustydud,
I'm glad the very knowledgeable users of this forum were able to give you all the tips and information about the various component. When I looked at your attached PDF, one thing I noticed is the 'single firewall' design between your precious SCADA system and the rest of the world. I would strongly suggest the the designers of your system take a look at "Guide to Industrial Control Systems (ICS) Security" by the US National Institute of Standards from June 2011. The design you have is for the most part on page 5-4, and is the least secure method of connection. That is, an outside agency only has to penetrate one device (the firewall) to touch your SCADA systems. The publication shows other connection designs that result in a more secure connection. As we know, now days there are so many forces that are constantly trying to break into systems, and SCADA systems are a much more popular target. See the publication at : http://csrc.nist.gov/publications/nistpubs/800-82/SP800-82-final.pdf Just my 2 cents worth....have a good weekend!
 
Let's clarify a few things for you rustydud.

The virtualization platform you will want is either VM Ware, Hyper V or RHEL. I advise you to go with VM Ware if you don't have a lot of knowledge in this area as they have market share and the best support.

Your drawing shows a SAN as the shared storage. This indicated a sever lack of knowledge from the designer as you would never put a SAN in this type of enviroment and things can go really bad real fast if you know know what your doing on a SAN with pure absolution.

Storage always goes in this order Local, DAS, NAS, SAN. and as you can see SAN is always the last choice and If you do go SAN you need one with dual active active controllers and if your uptime is of valve a redundant active failover SAN. This is frightening amount of money.On the low end 30K and on the higher end 100k plus.

I see a connection between the Virtual server hosts so are you planning HA ( High Availabilty ) or FT ( Fault Tolerance )or just VMotion?
 
Your drawing also shows 2 firewalls? In this setup it's not necessary a good firewall with multiple interfaces will do the trick. For that I like Cisco, SonicWall and Barracuda.

Cisco is not for the faint of heart so Sonicwall or Barracuda may be a better choice for you. If you have budget for it though a dual firewall solution is very secure but if you are going to have a second firewall I would use a secure crossing on the automation side.

For thin clients take a look at Thin manager and their hardware partners. You will get great support from them.

Make sure you company has volume licensing for server and desktop OS. Retail boxed or OEM licenses are a PITA in this type for setup.

For your Virtualization software VSphere will be the best choice. Here is a link to the various versions http://www.vmware.com/files/pdf/vsphere_pricing.pdf

If you want failover shared storage look into the VMware VSA which will allow you to use local storage on the physical servers as a fault tolerant Virtual SAN.
 

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