NLB confusion with 800xA History Installation
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As other comments had indicated, the NLB function is only required when there is High Availability configured in the History Servers, that is, there are two History Servers. In addition, with two History Servers, there is another network configured between the two History Servers, the CCN network. This CCN network is used to balance the data between the two servers only. In previous versions of 800xA History, (History 2.0), there was always a second network between the DCN's and the History Server(s), as the History Server(s), (whether or not there was a NLB configuration), did NOT reside on the 800xA C/S network by design. However with the move to the newest version of 800xA History, (History 6.0), it is required that the History Server(s) reside on the 800xA C/S network as the History Server(s) are now installed and upgraded via the SCC tool. It has always been implied that there should be a separate network between the DCN nodes and the History Server(s), as the traffic between these nodes is significant, and this is the preferred method. This is not to say that running all the data between the nodes via the 800xA C/S network will not work, however, it will produce more traffic on the 800xA C/S network than was originally planned. I have seen this configured both ways, and they appear to be working. Just be aware that this is not the implied design configuration.