See the NetBackup Getting Started Guide for description of the various NBU components.
The Master server is also the EMM server. It can be a different server, but in all my years working with NBU, I have never seen anyone installing EMM on a separate server.
Components of the Relational database is described in Chapter 18 of :
NetBackup Administrator's Guide for UNIX and Linux, Volume I
NetBackup Administrator's Guide for Windows, Volume I
under the topic:
About the NetBackup relational database
Extract:
Generally, the implementation of Sybase SQL Anywhere in the NetBackup catalog
is transparent. NetBackup installs Sybase SQL Anywhere during the master server
installation as a private, non-shared server for the NetBackup database (NBDB).
NBDB contains the NetBackup Authorization database, the Enterprise Media
Manager (EMM) data, as well as other NetBackup data that NetBackup services
use.
The same installation of Sybase SQL Anywhere is used for the optionally-licensed
product, Bare Metal Restore (BMR) and its associated database (BMRDB). The BMR
database is created during the BMR installation process.
By default, the NetBackup relational database (NBDB) is installed on the master
server. The master server is also the default location for the Enterprise Media
Manager (EMM) server. Since EMM is the primary user of NBDB, the NetBackup
database always resides on the same computer as the Enterprise Media Manager.
(See manual for more....)
