IDAS store-and-forward capability

IDAS includes "store-and-forward" capability, which protects against a temporary loss of data in the event that a remote IDAS cannot communicate with the AVEVA Historian.

Note: The store-and-forward option is not available if you have specified a failover IDAS.

If the remote IDAS cannot communicate with the Historian, all data currently being processed can be stored (cached) locally on the computer running IDAS. This hard drive location is called the store-and-forward path and is configurable using the Operations Control Management Console.

Note: Be sure to specify a valid Store Forward Path path. If the path is not valid and accessible, the store-and-forward functionality will fail.

If the IDAS is unable to send the data to the Historian, data is written to this path until the minimum threshold for the cache is reached, at which point no more data is stored. An error message is logged. Remote store-and-forward paths are not supported.

The following actions occur after the Historian becomes available again:

• The Historian verifies that the IDAS configuration information did not change while the IDAS was disconnected. The Historian attempts to restore data transmission from the IDAS. The IDAS stops local data caching and resumes sending data acquired from its data sources to the Historian.

• If Historian detects a difference between its version of the IDAS configuration, and the IDAS version, it dynamically reconfigures the IDAS to synchronize configuration information. The IDAS applies the changes and updates its local IDAS configuration file. Then, the Historian requests restoring data transmission from the IDAS.

• When the IDAS detects availability of the running Historian, it sends the store-and-forward data to the Historian at the same time it is sending real-time data.

After data from the store-and-forward cache is sent to the Historian, the cache is deleted from the IDAS computer.

Enabling IDAS store-and-forward mode increases system resources used by the IDAS service because the Store-and-Forward subsystem must be initialized and then maintained in standby mode, ready to accept data.

If the Historian computer has sufficient system resources, it is recommended to configure the local IDAS for store/forward as well. The local IDAS to continue store-and-forward data collection even if the other Historian subsystems are stopped.