Auerbach Publications
© 1999 CRC Press LLC 06/98
DATA COMMUNICATIONS MANAGEMENT
UNIX
AS
AN
A
PPLICATION
S
ERVER
IN
A
N
ETWORK
O
PERATING
S
YSTEM
E
NVIRONMENT
Scott Koegler
I N S I D E
Integrating with the Networking Environments, Network Server vs. Application Server, File Service, Printing across the Network, Internet/Intranet Services, Coping with a Mixed Environment
INTRODUCTION
Networks have evolved to become the mainstay of corporate America. Millions of personal computers are connected to network servers run-ning applications ranging from personal productivity to corporate ac-counting, yet the demands on the network continue to increase. These demands typically take two forms. The first is the availability of applica-tion software specifically tailored to the operaapplica-tions of an organizaapplica-tion. The second is the need to run processor-intensive applications in a per-sonal computing environment. Both of these situations require in-creased horsepower from individual computing components, and in some cases the required horsepower is just not available from net-worked components.
Today’s network architectures have been maximized to provide su-perb performance for file and print sharing tasks, but still may not always offer the level of performance required. Although the network operating system can provide network
servic-es, it is not typically optimized for application processing. Even in those cases where an application can be run on a network server, doing so may degrade the performance of the entire network, making the proposi-tion counterproductive.
P A Y O F F I D E A
Today’s distributed systems can become highly complex even when the network is homoge-neous. Maintaining a consistent NOS environ-ment lets network administrators develop a depth of understanding that often leads to better effi-ciencies in both day-to-day operations and in troubleshooting.
Even with the stunning advances in hardware systems and program-ming techniques, many companies find that the specific applications that fit their operations were created to run in multiuser environments rather than in network environments. In many cases this is the result of migrat-ing an application from a mainframe system and resultmigrat-ing programs re-main optimized for the multiuser rather than networked systems.
IS UNIX STILL GOOD FOR ANYTHING?
UNIX has a long history in the computing world. The simple fact that it is still around must mean more than that it is just hanging on. In fact, UNIX has enjoyed a resurgence of interest over the last couple years, largely because of the growth of the Internet. But UNIX has other strengths beyond the Internet.
The original advantages of UNIX were with its file system, multitask-ing kernel, and easy configurability. None of those early considerations have deteriorated, and they are still not fully duplicated in the newer op-erating systems. To be sure, both NetWare and NT have advantages with regard to market availability, commercial support, and a wide range of software options, but the basics still can be filled easily and inexpensive-ly with UNIX services. UNIX is a mature operating system and has been fairly well debugged and enjoys a wide, mostly independent, support group via the Internet. Its scalability, as of this writing, puts NetWare and NT Server in the little leagues.
INTEGRATING WITH THE NETWORKING ENVIRONMENTS
Networks have become commonplace, and the architecture has em-braced Ethernet as the predominant standard. Novell NetWare continues to maintain a 60% plus share of network server installations, and Mi-crosoft NT server continues to build an increasing market share. In the past, these operating systems imposed their own network protocols on their environment. Customer demand forced simplified integration, and both vendors supplied solutions and the third-party solutions, but the connectivity was generally less than seamless. The stunning rise in pop-ularity of the Internet and its associated TCP/IP protocol has had the ef-fect of forcing these two major network operating system suppliers to support this protocol as a ground-leveling standard. The net result to the user is that both Novell and Microsoft now supply the TCP/IP protocol as a part of their base product offering. In fact, Novell now offers TCP/IP as a selectable replacement for its long-standing IPX protocol.
What this means in a practical sense is that it is easier than ever for an organization to implement easily a variety of operating systems based on its business needs and application requirements rather than on what the net-working vendor’s dictates. It is now commonplace to find a corporate IT shop with a mixture of Novell and Microsoft servers on the same network.
WHY BOTHER WITH ANOTHER OS?
Although NetWare is a highly efficient file and print server, with Internet services included as part of the file server function, it does not offer the application services available in Windows NT. NT can provide a combi-nation of file and print services along with robust application service support and Internet services as well.
UNIX can supply nearly all the same facilities, and with TCP/IP now a networking mainstay, integrates into the LAN environment almost with-out being noticed. But, because there are few practical differences be-tween the available solutions, there needs to be some compelling reason to increase the complexity of the corporate LAN, even if only marginally. The most often cited reasons for installing a UNIX server in a LAN en-vironment fall into two categories: application support and price. In short, if an application is only available as a UNIX application, the choice is reduced to finding an application that runs on the existing network or installing the necessary UNIX resources. Organizations have somewhat more flexibility when installing a new application than when trying to in-tegrate a legacy system into a LAN environment. The good news in either of the situations is that connecting an existing UNIX application to a net-work is likely to be easier than either converting the function to a differ-ent application that is LAN based or redeveloping the application to run on the LAN. The combination of Windows and a good terminal emulator can deliver a very powerful combination that leverages the strengths of all the available applications and operating systems.
The second powerful consideration in favor of UNIX is the wide range of vendors offering similar versions of the same operating system. A by-product of this competition is the availability of highly competent operat-ing systems at very low prices. This is not to say that all UNIX OSs are the same. Some proprietary versions, like the IBM AIX and the DG version, weigh in at the same or greater costs than the popular Network Operating Systems (NOS). But at the other end of the range are systems like the SCO UNIX and, at the extreme low end, the Calera Linux. To be sure, there are differences in the variations in both capabilities and support, and these differences need to be factored into any decision, but depending on the level of in-house expertise, nearly all can be viable solutions.
One of the other things that can provide a benefit in the UNIX envi-ronment is the existence of a mature and widespread user-support com-munity. The UNIX community has been the premier example of noncommercial systems development for many years. Programs ranging from small utilities to full applications and even the operating system it-self have been available through the efforts of programmers around the world. Possibly the best example is the Linux version of UNIX, which was developed by a loosely coordinated group of programmers who each contributed his or her efforts to developing a state-of-the-art OS that is available, complete with source code, simply by downloading it. The
commercial versions of Linux add several features that make this user-supported system viable in a corporate environment. But at under $500 for a full license, it is a tough competitor.
OPERATIONAL CONSIDERATIONS
The introduction of multiple hardware and software platforms into a computing environment is a normal, if unwelcome, reality. It increases the range of knowledge required for internal support and adds to the list of vendors involved in the organization and, because of these factors, should not be entered into simply for the sake of adding a new environ-ment. However, given a valid business reason for doing so, there are tools and systems that minimize the impact.
Modern IT systems provide increased management capabilities through a variety of facilities. The availability of the Simple Network Management Protocol (SNMP) has made the management of heteroge-neous networks possible by providing a common protocol that nearly all system software and hardware vendors have implemented. With this kind of consistency, it is now possible to view a range of network servic-es through a common console. This means that the differencservic-es in man-agement of various platforms are minimized through the common interface. Day-to-day activities can be incorporated into a centralized sys-tem that decreases the load on the IT staff and reduces the integration of yet another operating system into a routine function.
NETWORK SERVER VERSUS APPLICATION SERVER
The role of the server needs to be taken into consideration when con-templating adding computing resources. In fact, one of the main reasons for adding a UNIX server to an existing networked environment is the different function the server will fill.
In a typical networked environment, the processing load is distributed, not always evenly, across the client PCs, the server, and the network ca-ble. Client/server systems attempt to do a better job at this load distribu-tion, but these systems have never really delivered on their promise of low cost, quick development, and high performance. In fact, because they distribute the load, they put increased demands on all the network components, leading to across-the-board upgrades for the entire network. Although certain applications like personal productivity, word pro-cessing, and spreadsheets, certainly work efficiently as client-side appli-cations, accounting, client information, and other database-type applications depend on centralized processing of some type. This may amount to file and print services, but more often involves some data re-trieval that depends on a server process to maintain the indexes or pro-cess SQL queries. These more-demanding services impose propro-cessing
loads on the server and end up degrading network performance as a whole. When the processing load increases and users begin to complain about the quality of service on the network, the upgrade spiral begins again. If the bottleneck is diagnosed as a server problem, the options for upgrading server hardware come into focus.
There is an increasing variety of server hardware available with in-creasingly faster CPUs and disk drives. The market for multiprocessor servers is even approaching the commodity level with systems of up to six CPUs in a single cabinet. So, while it is now possible to increase the horsepower available to the network server, running the server and an application in the same device concentrates the load. This is where the addition of an independent server can be justified.
Although there are numerous application types that can be run on a UNIX server, the most obvious include databases, mail systems, and In-ter/intranet servers. Relegating these processes to a separate device takes them out of the normal processing environment and segments the load. Any network administrator who contends with increasing loads on server processes knows that users notice when network performance degrades. It may be possible to avoid the eventual performance hits that result from increasing application support by strategically distributing particular ap-plication services to independent servers.
WHICH OS FOR WHICH SERVICE?
OSs are designed to provide certain specific services to multiple connect-ed computers and devices. Basic services such as file and print services were the initial reasons for installing NetWare and NT servers. All else be-ing equal, there is little reason to add a new OS to a network simply to deliver either of these services. However, if they already exist, or if they are being added for other reasons, there may be solid reasons to take ad-vantage of one or both of these facilities.
FILE SERVICE
UNIX can provide the same traditional services as part of its original range of processes as a multiuser processor. The file access optimization technique of directory caching and indexing pioneered by UNIX is now incorporated in nearly all server OSs. This means that UNIX can often provide excellent performance as a file server. Because of this, it may be advantageous to make use of otherwise unused disk space on the UNIX server. The issues involved in doing so will revolve around providing ac-cess to the files within the existing applications and directory structures already in place within the network.
The Novell NDS (NetWare Directory Service) provides possibly the best unified directory structure available by combining all available
com-puting resources into a tree-structured directory. Adding components to one part of the tree makes the new component available to any other component based on assigned access rights. A UNIX server (or any other server) that can participate in the NDS structure can be integrated seam-lessly into the network and become an additional storage resource. Users and application software may never be aware of the actual server soft-ware running in the new device. Selecting a version of UNIX that sup-ports NDS would be important in a NetWare environment because it would ease the integration of the new device and lessen the requirement for users to cope with another set of functions and commands.
The Microsoft ADSI (Active Directory Service Interfaces) does some of the same directory maintenance as NDS, but is not as widely deployed. This means that it is still unlikely that there are UNIX versions available that support ADSI. ADSI will support NDS, so there will be some long-term viability and cross-system access, but the control of directory access is likely to continue to be a major issue for debate for some time, as both Microsoft and Novell see it as strategic to their business.
Generally, there is nearly always a method for making a viable con-nection to a UNIX server across a LAN. All UNIX servers support TCP/IP, and most support the Novell IPX/SPX. There is less support for the Mi-crosoft NetBUI protocol, but it is increasingly likely that TCP/IP will be the common denominator in an integrated environment. Depending on the applications and access requirements, simple direct attachment to the UNIX system may suffice, which decreases the necessity for a sophisticat-ed directory system like NDS or ADSI. In fact, for small installations, it has been said that NDS can be more burdensome to set up and adminis-ter than the advantages it provides warrant.
PRINTING ACROSS THE NETWORK
The second mainstay of the NOS is print service. Once again, UNIX can provide excellent print services. When integrated into an NDS structure, UNIX printers become additional print resources to the network. But when these remote printers are used as fully competent print servers rather than as simply remote printers, there may be some productivity gains to be realized. This possibility exists but depends on several vari-ables that include the structure of the network, topology, and where the print jobs are serviced.
For simplicity, most UNIX versions provide print capability along with their overall file and connectivity services. As with file service, it is doubt-ful that adding a UNIX server for the purpose of providing print services could be justified without an underlying plan for the use of the UNIX sys-tem for other reasons. Nonetheless, if UNIX servers already exist within a network, their use as print servers may provide another resource for distributing the load.
INTERNET/INTRANET SERVICES
The demand for Internet and/or intranet capabilities is increasing. Com-panies who do not already have some kind of Internet capabilities are likely candidates for the near future. The Internet was born on UNIX sys-tems, meaning only that UNIX systems are natural hosts for most Internet services. Although both Novell and Microsoft offer Internet server capa-bilities within their respective server OS offerings, using the production server of a company as an Internet server can present problems. For these reasons, it may be advantageous to consider a UNIX platform for the primary Internet server of a company.
Most organizations provide Internet services so that users outside the company walls can have access to various information that the company wants to make available. In some cases this amounts to advertising and promotional material, or data files. It may include direct access to corpo-rate resources and data if the system is used as an intranet for employees and partners. In all cases, security and performance are issues to consider. The issue of security is beyond the scope of this article; however, whatever system is deployed, it must provide some kind of user valida-tion and firewall capabilities to provide the right informavalida-tion to the right users, and to deny access to all others. The most secure way to separate access is to separate the systems used to provide access. In considering the installation of Internet capabilities, both the risks and the advantages of providing these services from within the main network server should be considered.
Performance, or degraded performance, is an obvious consequence of adding Internet services to an existing server. It is not necessarily true that setting up Internet services on either a NetWare server or an NT serv-er will degrade the system pserv-erformance. For many companies, simply enabling the service will provide both the services and performance needed. In other circumstances, doing so can have significant impact on the entire network. The difference lies entirely on the services provided and the load produced by the combination of the applications and num-ber of users accessing them.
It is not possible to cover the range of applications and environments here. Particular attention must be devoted to the mid- and long-term use of the installation and to the relative capacities of the servers that will be hosting the Internet services. This analysis is similar to that required for any other application installation.
Nearly every UNIX server software vendor offers Internet server soft-ware. It is either a part of its base offering, or offered as an option. The cost of operating systems software is always a consideration, but not al-ways an indication of the worth of a product. And the fact that server software is bundled as a part of the system does not always mean that the included services will meet the needs of the organization. One appli-cation worth mentioning here is the Apache HTTP Internet server
(www.apache.org). This highly competent, user-supported application is available as a free download, and currently is estimated to support nearly 50% of today’s Internet sites. Apache is developed and supported by a user/developer community around the globe. For some organizations this may raise concerns about vendor responsiveness because there is no commercial vendor. But the success of this application is possibly direct-ly attributable to that fact, and to the fact that the system is supported by its developers, who all share a common interest in the system.
On the other hand, there are still compelling reasons to select systems like Windows NT for installations that require proprietary services. There is an increasing variety of applications and development kits that depend on server-side facilities like the Microsoft Active Server extensions and LiveWire from Novell. Just like the other applications discussed earlier, if the application chosen requires these facilities there may be few practical choices.
COPING WITH A MIXED ENVIRONMENT
Today’s distributed systems can become highly complex even when the network is homogeneous. Maintaining a consistent OS environment lets network administrators develop a depth of understanding that often leads to better efficiencies in both day-to-day operations and in trouble-shooting. If the option exists to maintain a single-OS network rather than to introduce multiple OS, the choice is clearly to keep things simple. In reality, there are numerous forces and considerations that lead to the ad-dition of multiple operating systems, and specifically UNIX. But this does not mean that the network will immediately become compromised be-cause support time is diluted.
The addition of proper network management systems that consolidate and even automate routine maintenance functions can make the differ-ence between stability and panic. The popularity of the SNMP for man-aging distributed systems can make this kind of support possible. There are numerous supporting application providers for the various operating systems. One foundation application is the HP OpenView that supports plug-in modules for monitoring different SNMP-enabled systems. The OS vendor should be checked to determine its support for SNMP. There are also different levels of support within the SNMP framework. Systems that provide interactive support and control in addition to simple monitoring facilities will pay off when the time comes to perform actual maintenance on a remote unit. Active maintenance allows such capabilities as remote reset and configuration.
A quick search of the Internet for “SNMP UNIX” using a favored search engine will provide a good sampling of providers of SNMP management systems.
ALL TOGETHER NOW
If you don’t have to, don’t do it. But, if your business requires computing services that go beyond the basic offerings of your current NOS, or if your users are already screaming about slow response times, adding a UNIX server to your LAN can be a good thing if done properly.
Scott Koegler is vice president of IT for a national printing franchise and specializes in networking subjects. He can be reached at skoegler@usa.net.
