System Management Servers

System Management Server (SMS) is used to manage your network clients. It can be used to install software on your network clients. SMS can also share applications while dynamically load balancing the server the user connects to, which also provides a bit of fault tolerance. SMS can be used to determine the hardware characteristics of your network clients and even inventory the software on your client computers. It is a very useful application.

SMS uses a slightly different organizational method than Windows NT Server. Instead of domains, SMS uses a hierarchical structure called a site. There are three different site types. These are:

•  Central Sites—A central site rests at the top of the SMS food chain. All other sites can be managed from a central site. A central site must have a copy of SQL Server available to store the SMS inventory for itself and all of its clients, or subsites. The SMS database is referred to as a site database. The central site is also a primary site, because it includes full administration of all the subsites and contains its own SMS database.

•  Primary Sites—A primary site also has a copy of SQL Server available to store the site database for itself and its subsites. A subsite can be either another primary site or a secondary site. A primary site includes the tools to administer the site as well as any subsites.

•  Secondary Sites—A secondary site does not have a site database. It places the information it collects into the primary site’s SMS database. A secondary site does not include any administrative capabilities. It is only a collection point.

What makes sites so important in this instance are the resources required by the various site types. At the very least, you must have a database server, such as an SQL Server, to store the SMS database. So, in essence, you need at least two servers: one for SQL Server and one for the SMS central site. If you require more than one SMS site, you can expect to allocate at least one database server to each three to five SMS primary sites. You may be able to increase the site-to-database ratio, depending on the site activity. Less active sites will need fewer database servers. You may also need to place primary sites, along with a database server, on the far end of a WAN connection to improve performance.

At a minimum, each SMS server should use a Pentium 133, 48MB of RAM, 1GB of hard disk storage, and a Fast Ethernet network adapter. If the site will be heavily used and you do not place the SMS helper services on other servers, you might need to increase the processor, memory, and storage requirements. SMS makes heavy use of the processor and I/O subsystem while it compresses, or decompresses, packages. A heavily used SMS server could run out of local storage quite rapidly, and you should be prepared for this contingency.

SNA Servers

SNA Server has three modes of operation. It can be a primary configuration server, a backup configuration server, or a member server. This follows a similar model for a Windows NT Server installation, in which each installation can be a primary domain controller, backup domain controller, or server. Much like a PDC manages the other computers (backup domain controllers, servers, and network clients), the account database, trust relationships, and shared resources, a primary configuration SNA Server installation manages the other SNA Server installations (backup configuration servers and member servers), 3270/5250 users, link services, logical units (LUs), and other relevant configuration information.

The same principle holds true for backup configuration servers and backup domain controllers. These servers obtain a copy of the configuration file from the primary configuration server, similar to the replicated account database from primary to backup domain controller, so that servers and connections can be managed. Just like a BDC cannot manage account information when the PDC is down, a backup configuration server cannot be used to modify the configuration of the current SNA Server installation when the primary configuration server is down.