Interface failover

With interface failover, you configure redundant interfaces—that is, you configure interface software on two different computers to record data from a single data source. If one computer fails, the redundant computer takes over. With redundant interfaces, you minimize data loss by ensuring that there is no single point of failure.

There are three types of interface failover: hot, warm, and cold.

• Hot failover

  Both interfaces collect data from a source but only one interface reports that data to Data Archive. If one interface fails, the redundant interface immediately begins sending data to Data Archive without any data loss. Because the data source is connected and sending data to two interfaces, this type of failover requires the most computing resources.

• Warm failover

  The redundant interface maintains a connection with the data source but does not collect data. If the primary interface fails, the redundant interface begins collecting and sending data to Data Archive. Minimal data loss might occur while the data-collection process starts.

• Cold failover

  The redundant interface only connects with the data source after the primary interface fails. Some data loss might occur while the connection process initiates (including tag loading) and while the data collection process starts. Because connections only occur when needed, this type of failover requires the least computing resources.

Most PI interfaces use the UniInt (Universal Interface) Failover service to manage failover. For more information on interface failover, see the UniInt Interface User Manual.

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