Network operating system
NOSfunctions -- such as providing file,
print, communication, database, application,
management, and other services to personal
computer clients -- may be provided several
ways. Each approach has its strengths and
environments in which it excels.This paper
compares the following operating systems
as candidates for selection as a NOS
Network Operating Systems (NOSs) have gone far beyond
their roots of file and print services. Other functions, such
as communications, database, application, and
management services, have become equally important in
corporate environments. Companies using NOSs have
found supporting large numbers of single-function servers
to be costly and complex. These companies have started
consolidating to a smaller number of larger, more
powerful, multifunction servers. This trend makes it
imperative for the NOS to have the flexibility to support
such configurations.
Multiporpose operating system
What follows are examples of multipurpose operating systems:
Digital OpenVMS Version 6.2
Microsoft Windows NT Server Version 3.51
IBM's AIX Version 4.1
SunSoft's Solaris Version 2.4
HP HP-UX Version 10.0
IBM OS/400 Version 3 Release 1
Network Operating System
The following are examples of network operating systems:
Novell NetWare V3.12
Novell NetWare V4.1
Banyan VINES
NOS Function
NOS functions are implemented two ways:
1.As a standalone operating environment that may or may not allow the support
of additional services, such as database or electronic messaging
2.As an additional service layered upon a general-purpose operating system,
such as Unix or OpenVMS
For the most part, standalone NOS environments provide the highest
performance when the only requirements are file and print services. They often
are less stable and robust when supporting other functions. When multifunction
servers are required, layering NOS functions on a general-purpose operating
system becomes the best choice.
Most NOSs reside in either the second or third tier of a distributed architecture.
General-purpose operating systems lend themselves better to multitier
architectures than single-purpose systems. This evaluation reviews the use of
each system as second-tier "application servers" in two-tier or multitiered
environments. No conclusions should be drawn from this evaluation about the
relative suitability of these systems as third-tier "enterprise servers."
Built a model of the features and functions
that are required for successful support of
NOS functions. The suppliers of the leading
standalone and multifunction NOS
environments were surveyed to determine
the specific capabilities of their products
NOS requirements
Does the NOS support multiprocessor systems?
Are these systems supported as asymmetric or symmetric
multiprocessing systems?
Can NOS functions be partitioned to run on more than one processor
simultaneously? Does the operating system support multiple
microprocessor architectures?
What is the minimum and maximum memory, disk cache, and disk
supported by each NOS?
What is the maximum number of file locks, open files, concurrent
clients, servers in any domain, and domains supported by each NOS.
Availability and reliability features
File locking, support of redundant arrays of inexpensive disks
(RAID), various types of client failover when a server fails, and
support of fault-tolerant hardware configurations are all important to
companies that rely on the network as a critical part of their day-today business operations.
Availability and Reliability
Clients supported
Most companies have a broad array of desktop devices. A NOS
must support all of the desktop devices being used in a company if it
is to be a viable candidate for adoption. Typical devices that must be
supported are systems running DOS, DOS/Windows, Windows for
Workgroups, Windows 95, Windows NT Workstation, Macintosh,
OS/2, and Unix. Other devices, such as X-Windows terminals,
character-cell terminals, and special-purpose devices that emulate a
character-cell terminal (teller terminals, point-of-sale devices, etc.),
should be supported as well.
Client Support
Network printing
Printing is one of the primary functions of a NOS When selecting
a NOS, companies must know the answers to the following
How many printers are supported per server?
Can multiple printers be driven by one print queue?
Can multiple print queues drive one printer?
Will the NOS deliver an alarm message to an operator if a
printing problem arises?
Will the NOS inform the user when a print job is completed?
Can the print function be managed remotely?
Network Printing
Network media
Many different network media types are in use in companies today.
To be successful, a NOS must support a broad collection of network
media, including all ethernet media, all token-ring media,
asynchronous and synchronous telephone lines, packet-switched data
networks (PSDN) like X.25, fiber-optic, and Integrated Services
Digital Network (ISDN). Without this support, it may be difficult for
a company to build the most optimal network infrastructure for its
Network Media
Network protocols
Connecting to the wire is the first part of building a networked
solution. The next step is supporting the network protocols on that
wire. Companies selecting a NOS must be comfortable that the
protocols on the corporate network are compatible with the NOS. The
protocols in this category are 3270 and asynchronous terminal
emulation, AppleTalk filing protocol (AFP), TCP/IP, Telnet, Simple
Mail Transfer Protocol (SMTP), Simple Network Management
Protocol (SNMP), SNA, SNA LU6.2, SNA Advanced Program-toProgram Communication (APPC), File Transfer Protocol (FTP),
Internetwork Packet Exchange/Sequenced Packet Exchange
(IPX/SPX), NetWare file services, NetWare print services, NetBIOS,
and NetBEUI. This category also considers whether the client can
access the server via an asynchronous line, a PSDN, the Internet, or
Network Protocol
Network services
This category evaluates NOS platforms to determine if they provide
the functions needed to support large corporate environments,
including support for directory services that allow users to access
network services without having to know the network address,
security services that control access to directory management
functions and determine whether the NOS supplier has committed to
supporting the tools, and services currently being specified by the
desktop management task force (DMTF).
Network Service
Server management
The server management category reviews the tools available to
manage NOS platforms, including
-audit trail functions,
-file management,
-user account management,
-error reporting,
-server performance reporting.
Companies need this information to administer NOS platforms in
a corporate environment.
Server management Support
Companies need to feel comfortable that corporate data assets
are secure. This category evaluates a NOS platforms' standards
compliance (B2 and C2 security ratings), support of access
control lists, disk quotas, automatic discovery of and
management of intruders, support of callback modems, support
of security management systems such as Kerberos, and whether
or not encryption services are available.
Companies consolidating many single-function servers into fewer
larger, multifunction servers must evaluate the NOS platform
infrastructure. A single-purpose operating system may provide
higher performance for file and print services but may require
companies to support another operating system as a platform for
application services. A general-purpose operating system can
support multifunction servers that can minimize management and
system costs. A multifunction platform may be able to support
multiuser time-sharing applications as well as supporting clients.
This category reviews NOS platform capability in this area.
Application development tools
NOS platforms are increasingly expected to support application
services as well as the traditional file and print services. This
category reviews the availability of third-generation languages
(3GLs), fourth-generation languages (4GLs), object-oriented
development tools, and tools for team programming on each
NOS platform.
Application Development Tool
Data access
As NOS platforms are expected to support more complex
applications, they are expected to support file access methods
and indexed file access methods. This category evaluates NOS
platform support of these file services.
Data Access
NOS platforms are expected to take part in complex, distributed,
multitier application architectures. This category reviews NOS
platform support of OSF's distributed computing environment
(DCE), object brokers, guaranteed messaging services, reliable
transaction routers, X.400 mail, and X.500 directory services
Database support
Database software is often part of the infrastructure of a
distributed application. This category evaluates which database
software is available on each NOS platform.
Database Support
This category reviews which application services are available
on each NOS platform. Application services include mail client,
mail server, word processing client, spreadsheet client,
integrated office suite, or Lotus Notes. Companies selecting a
NOS platform for both file/print services and application
services should consider NOS platforms with a strong ranking in
this category.

Network operating system comparison