1. Network operating system comparison

2. Introduction w 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

3. Summary w 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.

4. Multiporpose operating system w What follows are examples of multipurpose operating systems: w Digital OpenVMS Version 6.2 w Microsoft Windows NT Server Version 3.51 w IBM's AIX Version 4.1 w SunSoft's Solaris Version 2.4 w HP HP-UX Version 10.0 w IBM OS/400 Version 3 Release 1

5. Network Operating System w The following are examples of network operating systems: w Novell NetWare V3.12 w Novell NetWare V4.1 w Banyan VINES

6. NOS Function w NOS functions are implemented two ways: w 1.As a standalone operating environment that may or may not allow the support of additional services, such as database or electronic messaging w 2.As an additional service layered upon a general-purpose operating system, such as Unix or OpenVMS w 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. w 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."

7. Process w 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

8. NOS requirements w Architecture w Does the NOS support multiprocessor systems? w Are these systems supported as asymmetric or symmetric multiprocessing systems? w Can NOS functions be partitioned to run on more than one processor simultaneously? Does the operating system support multiple microprocessor architectures?

9. Architecture

10. w Scalability w What is the minimum and maximum memory, disk cache, and disk supported by each NOS? w What is the maximum number of file locks, open files, concurrent clients, servers in any domain, and domains supported by each NOS.

11. Scalability

12. 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-to- day business operations.

13. Availability and Reliability

14. 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.

15. Client Support

16. Network printing Printing is one of the primary functions of a NOS When selecting a NOS, companies must know the answers to the following questions: 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 ?

17. Network Printing

18. 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.

19. Network Media

20. 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-to- Program 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 ISDN.

21. Network Protocol

22. 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).

23. Network Service

24. 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.

25. Server management Support

26. Security 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.

27. Security

28. Functionality/utility 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.

29. Functionality/Utility

30. 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.

31. Application Development Tool

32. 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.

33. Data Access

34. Middleware 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

35. MiddleWare

36. 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.

37. Database Support

38. Applications 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.

39. Application

40. Suimmary