Hello Yanick,
To address your question in regards to setting up Multiple Heavy Forwarders (or Universal Forwarders) to watch the same Log files on an NFS Mount, you are correct this would cause a "Multiple" ingestions of the same Log, so you would see duplicate entries.
The best solution for this type of setup to monitor your Clustered Applications logs that are being written to an NFS Share would be to install the Splunk Universal Forwarder or Heavy Forwarder, depending on your needs, on the NFS Server. You would then configure the Universal Forwarder/Heavy Forwarder to monitor the Logs that your Cluster Application is writing to on the NFS Share.
The Universal Forwarder is a "Light Weight" version of Splunk that only forwards data to the Indexers for ingestion. The following link will provide information on the Splunk Universal Forwarder:
http://docs.splunk.com/Documentation/Forwarder/6.5.2/Forwarder/Abouttheuniversalforwarder
Now with that being said, alternatively you could have each of the Clustered Application Servers write to local logs and then use the Heavy Forwarder/Universal Forwarder installed on those Servers to monitor the Application Logs. This would provide a means of "tracking" possible issues based on Host Server sending the log data to the Indexers.
Thanks,
Jeff Thompson
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