Slimming TCO With Thin Clients - thin-client computing promises reduced total cost of ownership - Technology Information

NetPCs, NCs and Windows terminals all promise to reduce the fat of cost of ownership. So what does this diet require in terms of servers, networking tools and system software?

Thin client vendors promise a computing revolution with radical reductions in total cost of ownership and increased productivity at performance levels similar to or better than users enjoy now.

"We anticipate that very few changes will need to be made to an existing environment and that managers and users alike will be very happy with the performance level of thin clients," says Bruce Knaack, manager of the performance group of IBM Corp.'s Network Computer Division.

Any revolution, however, requires careful strategic planning. Knaack urges caution. "Network and system administrators alike need to tackle the thin client issue as they would any other proposed significant change in their environment. We recommend modeling performance characteristics by conducting a pilot study of five systems or so before proceeding too far down the road."

Got Milk?

Implementers of thin client technology face several choices and a considering introducing thin clients into their environments would do well to learn the differences, not only from a cost perspective, but also from the perspective of how each thin client model affects their server farms and backbones.

Thinking of thin clients as one thinks of milk might help.

The traditional PC makes up the whole milk category. You've got it all with the "fat PC": milk, cream, great taste, the works. Fat PCs run applications locally, with server access being limited to client database requests, network printing, and file saving and retrieving.

The 2 percent fat variety is the domain of the now not-so-popular NetPC, pioneered by Microsoft Corp. and Intel Corp. Essentially a centrally managed PC, the NetPC runs applications stored locally, on its own hard disk drive, downloading software only when a version update is required. Performance characteristics of this class of thin client would closely follow that of the traditional PC.

Network computers (NC) comprise the 1 percent fat milk category. Based on Java and following the Network Computer Reference Model, as defined and pioneered by Sun Microsystems Inc., Oracle Corp. and IBM, NC technology enables applets to be downloaded to the NC for execution. The idea is to make the Java applets more efficient and lean, providing just what the user needs at the time rather than forcing the client to download the typical multimegabit application. Locally caching the applets removes the load of executing them from the server. Without permanent storage, however, the applets need to be downloaded across the network at every reboot.

The skim milk arena belongs to Windows terminals. Windows terminals rely solely on server-based applications. Users of X Window System terminals will find the Windows terminal model to be quite familiar. A very small operating system runs on the Windows terminal to allow it to connect to a Windows NT server, which is running multiuser code such as Microsoft's Windows Terminal Server (formerly code-named Hydra) running the T.Share protocol, or Citrix WinFrame running the Independent Computing Architecture (ICA-3) protocol. Processing occurs and data resides on the server, while the client concentrates on graphics and display functions.

Many of us grew up on whole milk. We probably grimaced a little when we tried all the other varieties. Vendors of thin clients have a large task. Whether manufacturers of the 2 percent NetPC or the skim milk Windows terminal, they need to produce a product that users, system administrators and network managers alike will drink. One of the best ways to make thin clients palatable is to meet or exceed the performance levels to which users of traditional PCs have grown accustomed.

There is room and a need for various client types. Vendors such as IBM and Neoware (King of Prussia, Pa.) offer clients that go both ways, providing access to multiuser Windows NT applications while providing the benefits of Java. "One of the misconceptions about thin clients is that they are `anti-Microsoft,' or `anti-PC,"' says Michael Kantrowitz, executive vice president of Neoware, one of the earliest providers of thin clients. "While it is true that the original Java NC was designed as a competitor to the PC, the products that people are actually buying in volume are what we call `universal thin clients,' machines that run Windows applications on a central server, and also include terminal emulation, UNIX connectivity, a Web browser, e-mail and Java. These thin clients offer an alternative to the PC that is easier to use and administer, and they're mostly installed in environments alongside PCs."

No matter what category of thin client, commonalties emerge as to server, client, network and application performance that administrators should consider before embarking into thin client territory.

Rambo Servers?

Are you champing at the bit to get your gigahertz, eight-way Pentium II mega-powerhouse? Don't rely on thin clients to realize your dream. Well, not totally, at least.

Compaq Computer Corp. paints a rosy picture regarding server requirements and thin clients. The November 1997 white paper "Citrix WinFrame and Compaq Servers" summarizes the effects of placing various user loads on Compaq servers, ranging from a single Prosignia 200 to the top-of-the-line four-processor ProLiant 7000, running Citrix's WinFrame.

User loads were categorized as "light" -- a user working with a simple document using Word or Excel -- and "heavy" -- a user working with several complex documents requiring several instances of Word, Excel and/or PowerPoint.

Compaq's tests revealed that even a 90-MHz Pentium Prosignia 300 could support 20 light and 10 heavy users. The four-processor ProLiant 7000 could handle up to 175 light and 100 heavy users.

Compaq pointed to memory as one of the most important system resources to monitor and tune, recommending 17 MB for base operating system code, 8 MB for each heavy user and 4 MB for each light user. Tektronix Inc. (Beaverton, Ore.), maker of WinDD, a multiuser Windows NT variant based on Citrix WinFrame, agrees that memory is the most important factor. Regarding server processing power, Tim Kellog, product marketing manager for thin clients with Tektronix, says, "Tektronix has customers supporting 100+ users per server. Servers can support approximately 25 users per processor, and many four-processor devices are available, offering better total cost of ownership."

IBM's Knaack cites similar findings in the processor area. Regarding server memory, however, IBM is a little more conservative, feeling that 4 to 8 MB is "a little low. We're seeing good results when running 10 MB to 12MB of memory per user beyond that required by the base operating system," says Knaack.

Clients Aren't off the Hook

Being thin doesn't mean that your clients can be weak. Client machines, in particular, have to excel in graphics performance. whereas you will be very concerned with bus and processor speeds when purchasing a fat client, your attention will turn to graphics processors and available resolution when considering thin clients.

According to Tektronix's Kellog, a thin client's performance "depends on several factors, including how the software is tuned and the processor speed." Still, there is apparently no need to go overboard in the processor area. Kellog continues, "The faster the processor, the faster the client, up to about 100 MHz; beyond 100 MHz, there is little additional speed gain." So, while we goble up 200+-MHz PCs, the thin client's simpler focus on graphics performance proves to be a money-saving advantage.

Jeff McNaught, senior director and general manager with Wyse Technology Inc. (San Jose, Calif.), a leading producer of Windows terminals, adds, "Thin clients, as in Windows terminals, perform as well as the server to which they are attached, since they are merely display devices that show what's happening on the large computer. Network computers require their own computing capabilities. Compared in a vacuum, the NC needs more powerful components, but that comparison is meaningless, since neither machine works except in a connected environment. And there what matters most is the work you are trying to o and the servers you are using, not the relative performance of the desktop devices."

Breaking the Backbone?

If your technologically savvy and progressive network manager is looking for an excuse to get that 100-Mbps switched Ethernet network to the desktop, he or she won't find it with thin clients. Thin client vendors categorically deny that networks will crumble under the weight of tremendous network traffic. In fact, most vendors offer all the good taste of a traditional PC environment without the network fat.

"In reality, thin clients generate very little network traffic," states Neoware's Kantrowitz. "Our customers are able to connect hundreds of thin clients to existing Ethernet networks without making any changes. It's just not true that thin clients require significant changes to existing networks or servers."

Neoware's white paper "Network Computers, NetPCs and network Traffic" contain the results of a comparative test conducted between a Neoware NC accessing a Windows NT Server running NTrigue 3.0 multiuser Windows NT code from Insignia Solutions Inc. (Santa Clara, Calif.), using the ICA-3 protocol, and an unnamed diskless NetPC. All tests were conducted on a shared 10-Mbps Ethernet network.

Typical office applications such as Microsoft Word, Excel and Power-Point, as well as Quark, were run using both machines. Various documents were opened and typical operations were performed on the documents from each client type. The test was conducted for 1 hour.

Neoware's results cite that the NC generated 1.5 MB of network traffic in the hour-long test as opposed to the 20 MB of network traffic generated by the NetPC. Taking it one step further, Neoware calculated that, given the efficiency of shared Ethernet, a customer could connect 900 NCs to their network, as opposed to 66 NetPCs.

Tektronix takes a different angle on the network performance issue in its white paper "Network Loading Characteristics of ICA-3 and X11." Tektronix used the popular Win Tach and WinBench performance benchmarks from Texas Instruments Inc. (Dallas) and Ziff-Davis Publishing Co. (New York), respectively. Tektronix claims that, for typical office applications, its WinDD product was "six to nine times as efficient as any X11-based product." So, a good question to ask is this: "If the X Window System protocol has been successfully run on Ethernet networks for this long, how can you argue with the more efficient ICA-3?"

Jim Fulton, vice president, strategy, at Network Computing Devices Inc. (Mountain View, Calif.), concurs: "Most thin clients are designed specifically for use in shared LANs using typical 10-Mbps Ethernet. Many are even used over wide-area networks and even dial-up lines. Thin clients offload chunky file-transfer traffic from the network and replace it with much smoother and more predictable graphics command streams that are kinder and gentler on routers and other infrastructure."

Killer Apps?

OK, what about the applications we run, something about which we might feel rather powerless to do anything? One of the biggest advantages of a multiuser NT variant such as Microsoft's Windows Terminal Server or Citrix's WinFrame is its ability to let us use the same off-the-shelf applications that we typically run around and install on everyone's PC. Still, there any general rules of thumb to consider.

Both Compaq and Tektronix recommend using 32-bit applications as much as possible. Compaq claims that the overhead of translating 16-bit code to 32-bit coed is good for a 20 percent decrease in the number of supportable users on a WinFrame server and a 25 percent increase in the memory requirement per user.

Microsoft provides more details regarding the development of well-behaved multiuser NT applications in the white paper "Optimizing Applications for Windows NT `Hydra' (Windows NT 4.0 and 5.0)," which can be found on the TechNet CD. Among the many guidelines presented within the paper, developers are encouraged to avoid storing local data constructs in global locations, beware of memory leaks, and minimize the use of animation and other items that consume a lot of CPU cycles. Of course, developers should pay attention to these things anyway. However, the multi-user NT environment demands special attention.

Amid the hype, thin clients promise to deliver superior performance without the management headaches or cost of traditional PCs or even ill-fated NetPCs. However, there is a need for caution and for a well-planned approach to the technology. In the long term, however, it appears that thin clients, in whatever form, are a winning proposition for enterprises that know their performance requirements and implement them intelligently.

David B. Miller is a network/server engineer for a Fortune 50 information services firm (Purchase, N.Y.). Contact him at millerdb@glinchnet.com.

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