Forward: I'm using Java 6u45, WebLogic 10.3.6, and Ubuntu Desktop 14.04 64-bit.
I just started as a student assistant at one of my state's IT offices. On my first day I was tasked with testing WebLogic on Ubuntu (Windows isn't cases sensitive, causing later issues because WebLogic is...). I started messing around with clustering, and now my setup is as follows:
1 Ubuntu machine
1 domain
6 servers: Admin server, wls1-4, and wlsmaster (wlsmaster was supposed to be what wls1 and wls2 reported to within the cluster because I set the cluster to be unicast, but that's a secondary question for now).
2 clusters: cluster1 and cluster2. wls1, wls2, and wlsmaster are on cluster1. wls3 and 4 are on cluster2.
Given my setup, do I even need to use node manager because I'm only using one physical machine? Secondary question; if I want to use unicast, how do I set the master? $state uses unicast for what few Weblogic servers we have, so I was told to check that out.
A few things:
No, you don't necessarily have to use a nodemanager, but it will make your life easier. When you log into the weblogic admin console and attempt to start one of your servers e.g. wls1-4, the Admin server will attempt to talk to the node manager to start the servers. Without the nodemanager you will have to start each server individually using the startManagedWebLogic.sh script and if you need to bring servers up and down often it will be very annoying.
With regards to Unicast it is pretty easy to set up (we just leave all the default values alone). Here is the pertinent info from the Oracle Docs:
"Each of the Managed Servers in a WebLogic Server cluster has a name. For unicast clusters, WebLogic Server reads these Managed Server names and then sorts them into an ordered list by alphanumeric name. The first 10 Managed Servers in the list (up to 10 Managed Servers) become the first unicast clustering group. The second set of 10 Managed Servers (if applicable) becomes the second group, and so on until all Managed Servers in the cluster are organized into groups of 10 Managed Servers or less. The first Managed Server for each group becomes the group leader for the other (up to) nine Managed Servers in the group."
So you will want to name your master servers in such a way that they are the first alphanumerically in the cluster. That said, for your use case I doubt you need those master servers as all. Just have 2 clusters, one with wls1-2 and one with wls3-4.