Advanced File and Print Server Quick Start Guide

Multiple server networks

When the network expands to include multiple server systems, the administrator must understand:

server roles
structuring the network

Server roles

Each server has a defined role in a domain. An Advanced Server domain is a group of one or more servers and any number of network clients that share security policies, including a single user accounts database. All servers in a domain use the same user accounts database to validate logon requests.

NOTE: An Advanced Server domain is the same as a Windows NT domain. Do not confuse Advanced Server domains with TCP/IP network protocol domains. A TCP/IP domain describes part of the TCP/IP Internet and is not related to Advanced Server domains.

The first server installed in a domain must be a primary server. Any server added to that domain must be a backup server.

primary: The primary server or "primary domain controller" (PDC) maintains the master copy of the domain's user accounts database, which contains account information for all users in the domain. A copy of the user accounts database is automatically replicated from the PDC to each backup server at regular intervals.
backup: Each backup server periodically receives a copy of the user accounts database from the primary server so it can also authenticate users and control access to shared resources.
A backup server can improve network performance by taking over some of the PDC's work load and can improve network reliability by validating logon requests when the PDC is unavailable. If the PDC is completely out of service, you can change the role of a backup server to primary.

Structuring the network

Ease of administration and accessibility of resources (as well as performance and reliability) depend on a carefully structured network. Establish domains, erver roles, and trust relationships based on your network needs:

If you have only one server, set up a single domain with a primary domain controller.
As your network grows and performance and reliability become more critical factors, set up a domain with a single primary domain controller and one or more backup servers to share the work load.
If the servers and clients fall into departmental (or other logical) groups, create a network with several, smaller domains that are easier to manage. For centralized administration, designate one or more master domains and establish trust relationships between domains as needed.
If the network is split across subnets (using routers or dial-up connections), configure WINS on the server and each client. See SCO Advanced Server Administration Guide, Chapter 5, Implementing WINS.