Slimming TCO With Thin Clients

ENT, March 4, 1998 by David B. Miller

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."