1    Introduction to Sharing Software

This chapter describes the concept of software sharing and the components that make up a software sharing environment.

1.1    What is Software Sharing?

A server is a computer system that serves another system by providing something that the other system wants or needs. The other system is called a client. A given server can serve one or many clients. Computers in a network can share disk space, lists of names, software kits, processing services, and other entities.

For sharing software using Dataless Management Services (DMS) and Remote Installation Services (RIS), the server supplies software, software kits, and disk space for clients to use.

The DMS and RIS services let you share software in the following ways:

• DMS sets up a system in which you can save disk space by sharing the actual operating system software between computers. Without DMS, each computer has a copy of its operating system software on its own disk. With DMS, one computer, acting as a DMS server, stores the software in a special area (called the DMS area) on its disk. Other computers, called DMS clients, run by accessing the software across the Local Area Network (LAN) instead of from their local disks.

• RIS sets up a system similar to the DMS system except that what is shared is one or more installable software kits instead of the actual operating system. With RIS, you can buy only one copy of a given kit. One computer, the RIS server, stores the kit in a special area (called the RIS area) on its disk. Other computers, called RIS clients, install the software onto their own disks by accessing it across the network instead of from locally mounted distribution media (such as a CD-ROM).

The DMS and RIS utilities share architectural similarities; the primary differences are in the contents of their respective server disk areas.

1.2    Benefits of Sharing Software

You can reduce your software and hardware costs by sharing software between computers. When you share software, several of the computers in your local area network (LAN) use a single copy of a given piece of software. This reduces the need for multiple copies of the same software and reduces the disk space required for software storage.

You are not limited to sharing one piece of software; you can share virtually all of your Digital UNIX system software.

1.3    Software Sharing Environment

The following components make up the environment for software sharing:

• A server

  The server's system administrator prepares the server for RIS or DMS by installing the Digital UNIX operating system and ensuring that the server is connected to a LAN. A single server can serve both DMS and RIS clients, however a client cannot be registered to both DMS and RIS.

• A distribution device on the server

  For Digital UNIX servers, the distribution device is a CD-ROM optical disk drive. You transfer or link the software subsets for one or more specific products and architectures from the distribution media to the RIS or DMS areas on the server. Registered clients can then access the software.

• A Local Area Network (LAN)

  You must set up the server and all client processors as hosts on the LAN (using Ethernet, FDDI, or Token Ring for RIS and Ethernet or FDDI for DMS). Clients use the LAN to access the server's RIS and DMS areas.

• Clients

  RIS clients are systems that can run the operating system for which the server provides kits. Typically, clients are systems that run the Digital UNIX operating system; only these processors can install the base operating system from a Digital UNIX server. Layered products can be installed after the client's operating system is running if the processor supports the setld utility.

  DMS clients must be capable of booting over Ethernet or FDDI using the bootp and tftp protocols. Most Alpha workstations and deskside servers have this capability, but some data center servers cannot be configured as DMS clients. Consult your system's user guide and related documentation to determine whether it supports bootp and tftp over Ethernet or FDDI.