Use a redundant AVEVA Historian Server

An AVEVA Historian may be configured to have a symmetrical partner AVEVA Historian that can be used as a backup if the primary, or main, historian is not available. This is known as a "redundant historian" setup. No client configuration is required to take advantage of a redundant historian.

When the primary historian is unavailable, a Historian Client automatically switches over to the configured partner historian. The client remains connected to the partner historian, even when the primary historian becomes available again. A Historian Client switches back to an available primary historian if it fails to connect to the partner or during a new attempt to connect to the primary historian, such as when restarting Trend.

When a Historian Client successfully connects to either the primary historian or its partner, the following columns are updated with the connected historian server name in the tags list of the selected tags:

• Server

• I/O Address

The historian name shown in the Tag Picker is always the name of the primary historian, even when the client is connected to the partner.

There is no automatic synchronization built in to the redundant historian setup; it is up to the historian server administrator to make sure that the two historians in the pair are symmetrical and synchronized.

If the SQL Server Service is running while Historian Service is not running, this is not recognized by the Historian Client as a scenario in which the Historian Server is unavailable.