With ClearSCADA, you can run multiple ClearSCADA database server applications on a single server machine. For example, if you have a high-specification server, you could use it to run several ClearSCADA Permanent Standby servers at the same time. This functionality provides two key benefits:
- Your system makes better use of your server hardware's resources.
- The cost of using Permanent Standby servers may be reduced. Investing in one, higher specification server may be a better option than buying separate server hardware for each server application.
When you first install ClearSCADA on your server hardware, one 'instance' of a ClearSCADA database server is installed. This instance is a Main server and its registry settings are created as part of the import process. When you configure the server (using the Server Configuration Tool), the server's registry settings are updated accordingly.
After installing the first ClearSCADA server on a machine, you can use the Database Manager to add extra database instances. These instances are ClearSCADA servers that run on the same machine as the first ClearSCADA server.When you create a database instance, ClearSCADA adds the registry settings for that database instance automatically. You can then use the Server Configuration Tool to set up the database instance in the same way as any other ClearSCADA server.
Typically, you would use the Database Manager to add database instances for Permanent Standby servers. This is because Permanent Standby servers do not require large amounts of system resources, and so are ideal candidates for sharing server resources. Importantly, they do not switch to Main (Main servers require far more system resources than Standby servers).
However, you can configure a database instance to be any type of server - Main, Standby or Permanent Standby. But if you are going to use a database instance as a Main or Standby, you need to consider the:
- Amount of resources required should all of the 'database instances' go Main at the same time.
- Potential effects on system performance, should the server hardware have insufficient resources.
- Cost of server hardware capable of running the database instances simultaneously without being affected by slow performance.It may be more cost-effective to set up your ClearSCADA database servers on separate, lower specification machines.
To add one or more database instances to a single machine (that already has a ClearSCADA database server installed):
- Display the Database Manager
- Add a Database Instance
- Add a license for the database instance (see Licensing a Database Instance)
- Run the Server Icon for a Database Instance
- Start a Database Instance.
Further Information
The rest of the topics in this guide provide information on using the Database Manager to view, delete, run, and stop database instances. For more information, see the topics that are listed in the gray footer section at the bottom of this topic. Select the relevant entry to display the topic that you require.
For information on the different types of server architecture, including Hot-Standby Pairs (Main-Standby), Triple Standby, and Permanent Standby servers, see System Architectures in the ClearSCADA Guide to Server Administration.