The distributed computing environment

Distributed computing means the sharing of resources (such as printers, databases, or mail) across machines on the network. With distributed computing, various types of server systems fulfill client systems' requests for data. Occasionally, the server and client software exists on the same machine.

The SCOadmin managers facilitate distributed and remote system administration of SCO OpenServer servers and clients. For information on using these managers, see ``Administering other systems with SCOadmin managers''.

SCO OpenServer supports the following types of servers:

Application servers

Many applications, such as DocView, SCOcalendar, and many relational database management systems, use a client-server model wherein the data resides on one or more application servers. To access the data, users on client machines run a program on the local CPU, which transfers data over a networking protocol such as TCP/IP. The program may be on a local filesystem or it may be mounted via NFS from a file server. In most cases, the user is unaware that the data does not reside on the local system.

In addition, many multiuser host applications are available for SCO OpenServer systems. You can access them remotely via your network using telnet, rlogin, and other terminal emulation programs.

File servers

File servers, running programs such as Network File System (NFS), Microsoft LAN Manager for SCO Systems, and NetWare, allow users on client machines to transparently access files from server-exported filesystems on the local host. Use of file servers enables you to more effectively balance the disk space load between various machines on your network and to share files between machines running different operating systems.

Installation servers

The SCO OpenServer networked installation capabilities enable you to install the entire operating system or operating system components over the network.

Mail servers

Both mail transfer agents supported by SCO OpenServer, MMDF (the Multichannel Memorandum Distribution Facility) and sendmail, allow for operation over the network and have the ability to interact with other mailers through mail gateways.

Name servers

Name servers, such as the Domain Name Service (DNS) and the Network Information Service (NIS), maintain repositories of network and host names and addresses, and are queried by programs such as mail and remote login programs operating on client computers. SCO OpenServer supports a variety of local, remote, and distributed name services. Using a name server becomes appropriate as your network grows large or connects to the Internet.

Network management servers

Several programs and protocols provide a framework for managing your users, systems, and network resources.

Most SCOadmin managers allow you to remotely manage system users and resources, such as printers, filesystems, and user accounts.

The Simple Network Management Protocol (SNMP) enables you to remotely manage other network machines and devices running SNMP. For example, you can mark an interface as being down, modify routing information, or generate statistics that pinpoint performance issues.

With the Network Information Service (NIS) or the TCP/IP program rdist(TC), you can maintain central repositories of system files, such as /etc/hosts, /etc/passwd, and /etc/group, which are either served to or pushed onto other machines as appropriate.

Print servers

You can print from your local SCO OpenServer system:

• locally, by using lp(C).

• remotely, to a printer connected to an SCO OpenServer system or a UNIX system via TCP/IP, by using Remote Line Printing (RLP).

• remotely, to a printer connected to a NetWare server, using lp(C) and SCO Gateway for NetWare's print capabilities.

• remotely, to a Hewlett-Packard^® JetDirect printer connected directly to the network.

• Other TCP/IP-connected systems, via Remote Line Printing (RLP).

• A DOS, OS/2, or MacIntosh computer using PC-NFS.

• A DOS computer running PC-Interface for DOS.

Time servers

Many database programs depend on time synchronization across the network to allow for effective file locking and authentication. The SCO OpenServer Desktop and Enterprise systems include two TCP/IP protocols, the Network Time Protocol (NTP) and the Time Synchronization Protocol (TSP), which allow for time synchronization on Internet-connected and non-Internet-connected networks, respectively.

User account servers

To effectively manage user accounts across the network:

• Use the Network Information Service (NIS) to create and maintain distributed user accounts from a single master NIS server.

• Use the automount facility of NFS in conjunction with NIS to make distributed home directories available to any system in an NIS domain.

• Use the SCOadmin Account Manager to manage both local and remote user account information.

• Use the useradd(ADM) command to add, modify, or delete account information on a remote host.