I was installing a 4-node Exchange 2007/SQL 2005/Virtual Server/File Cluster for a customer and noticed a cluster group called PBX-Clustergroup-Servername (replacing servername with the same of the cluster node). Since this was my first time installing Exchange 2007 on a cluster, my assumption was the PBX name was tied to Exchange 2007 unified communications role. It turns out, this is not the case
After doing some research, I found that the cluster group is created by NetBackup’s network backup software.
NetBackup 6.0 contains features that are dependent on a new Common Services Framework (CSF) called, VERITAS Private Branch Exchange (PBX). PBX helps limit the number of TCP/IP ports used by many new features in NetBackup. In addition, it allows all socket communication to take place while connecting through a single port. The PBX port number is 1556. For more information about PBX and configuring NetBackup ports, refer to the NetBackup System Administrator’s Guide, Volume 1. Because PBX is required for all NetBackup products, its installation is part of the NetBackup installation procedure unless it is already present on the system.
Hope this information helps those investigating what or who created that cluster group without asking.