Technical data

2
Understanding OpenVMS and UNIX
Implementations
An important step in planning a network host implementation is to gain an
understanding of the computing environments in which the network services will
run. Compaq Tru64 UNIX implementations of TCP/IP Services are often ported to
OpenVMS. As a result, they often appear to be identical. However, there are many
significant differences. This chapter describes key implementation differences
between UNIX and OpenVMS networks. The following topics are discussed:
• Evaluating the computing environment
• File compatibility
• Portability
• Determining which file system to use
Things to Consider
In planning your TCP/IP Services environment, consider the following:
• Do I need to migrate from one operating system to the other?
• Do I need to set up a system that coexists with multiple operating systems?
• Should I choose a Files–11 file system or a container file system?
2.1 Evaluating the Computing Environment
The issues of working in a heterogeneous computing environment that includes
OpenVMS and Tru64 UNIX operating systems are complex. Consider these
concepts when evaluating or implementing an interoperability strategy:
• Migration occurs when software applications are rewritten as necessary to be
ported from one operating system to the other. In a general sense, not only the
applications but also the users migrate to another system. Migration implies a
gradual replacement of the original system with the new system.
• Coexistence occurs when two or more systems, such as OpenVMS and
Tru64 UNIX, are maintained as part of a larger, heterogeneous computing
environment. The amount of interoperability varies with the individual
configurations. It is possible to set up nearly identical network configurations,
thereby reducing maintenance.
2.1.1 Understanding the Open Systems Concept
The client/server model of computing means that users running applications on
their PCs and workstations are networked with larger departmental systems. The
departmental systems provide a variety of services to the clients, such as access to
common database, print, and backup/archive services.
To best serve this model of computing, the systems must be open. Open
environments support interoperability and application portability and enable
developers and users to easily use different platforms. The OpenVMS operating
system is an open system with an extensive list of functions.
Understanding OpenVMS and UNIX Implementations 2–1