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The only configuration needed in the Archives.xml is the location of the catalogue (the seamless integration uses the elastic search catalogue and not the Geonetwork catalogue). In addition the url of the fileserver at which the data is available should be configured.
The datafolder is optional. It is used by the pi-service (rest and soap) to read the data. If the datafolder is configured the data is read from the folder directly and not from THREDDS. Reading the data directly from disk is faster than reading the data from THREDDS. So the datafolder should be the root of the datafolder of the archive as it is on the server on which the pi-service is configured.
To test if the url for the catalogue is correct you can paste the url in your browser. If the config is correct you should see a response simular to the one below.
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