ClearSCADA can run in a virtual environment, with one or more virtual servers running on the same hardware. When using virtualization, there are several considerations you need to make relating to licensing, hardware and software requirements:
- Licensing:
To comply with ClearSCADA licensing terms, you must acquire a license for each copy of ClearSCADA that runs on a virtual server.
If you are using dongles, you need to set up a hardware ‘pass-through’ for the USB ports. This will allow the hardware’s USB ports to be associated with the virtual servers correctly. You also need to ensure that the hardware has a sufficient number of USB ports available (one USB port per copy of ClearSCADA is required).
If you are using license files, you should set up the virtual machine (VM) environment to use a fixed MAC Address for the virtual ethernet card and a fixed ID for the system disk.
Licensing for multiple-server architectures (redundancy) works in the same way as non-virtualized ClearSCADA servers, with a license required for each copy of ClearSCADA. We recommend that the Main server in a multiple-server architecture is located on different hardware to the Standby server(s), as this will allow for redundancy in the event of a hardware failure.
- Hardware Requirements:
You need to make sure that the hardware that runs the virtual servers has sufficient:
- Disk space
- RAM and processor cores
- Disk performance.
Each virtual server requires the same resources as a non-virtualized ClearSCADA server (see Recommended Server Configurations). So the hardware that is running the virtual servers needs to have sufficient resources for all of the virtual servers combined. For example, if the hardware is running two virtual ClearSCADA servers, one with 10,000 database objects and one with 50,000 database objects, you would need to calculate:
- The requirements for the server with 10,000 database objects. This is the same as a non-virtualized ClearSCADA server (namely a quad-core server class processor, 8GB RAM, 25GB free space on high performance disks for configuration, and so on, with a separate 250GB high performance disk system for storing historic data).
- The requirements for the server with 50,000 database objects. Again, this is the same as a non-virtualized ClearSCADA server (namely a quad-core server class processor, 8GB RAM, 25GB free space on high performance disks for configuration and so on, with a separate 500GB high performance disk system for storing historic data).
The hardware needs at least the combined total resources required by the virtual servers. So in this example, the hardware requires at least 2 quad-core processors, 16GB RAM, 50GB free space on high performance disks for configuration and so on, with a separate 750GB high performance disk system for storing historic data.
NOTE: The minimum requirements defined above are those required by ClearSCADA in a virtual server environment. The minimum requirements for the virtual server technology may exceed the ClearSCADA limits. For more information, please refer to the documentation for your virtual server solution.
When using virtualization, you also need to consider disk access for the virtual servers. Performance can be affected by multiple virtual servers attempting to access the same disk at the same time. So where possible, you should use separate disks to distribute load appropriately.
For ultimate performance, you could use four high performance disks for each virtual server, with one disk for historic, one for logging, one for the event journal, and one for the operating system and ClearSCADA database. However, due to the high cost of such a setup, you may choose to compromise by distributing the load across fewer disks.
- Software Requirements:
ClearSCADA has been tested with the following server virtualization products:
- VMWare ESXi Version 4
- VMWare ESXi Version 5.