Tuesday, January 23, 2007

Which Operating System For Your Intranet

It's enough to make a marketeer drool. By the year 2000, Forrester Researchestimates that the public network server hardware market will hit $2.5 billion,but that's small change. The "intranet" market of corporate networksbased on Internet technology is expected to be five to 10 times larger.With that much at stake, it's little wonder that Jamie Zartman, Meta Groupprogram director, compares server manufacturers to 2,000 supertankers makinga mid-course correction. Just about every operating system from IBM's mainframe-basedMVS to Microsoft's NT is being repositioned as an Internet server platform.It's too early for the prognosticators to single out wi nners, but the victoris clear in one large market segment--Internet service providers (ISPs).

Among ISPs, Unix rules, and it's worth examining why some of the most experiencedTCP/IP users refuse even to contemplate giving up the OS. Of course, asMichael O'Dell, UUNET Technologies vice president of research and development,puts it, Unix "is the devil you know versus the one you don't."Still, the issue is much larger and has relevance for large intranet buildersas well as those shopping for an ISP.

For ISPs, Unix is a natural because the openness of its variants--like BerkeleySoftware Design Inc. (BSDI) and LINUX--allows easy access for kernel performancetweaking as well as security enhancements. Many ISPs also insist that onlyUnix provides the scalability they need. Amo ng the many variations of Unix,Sun Microsystems SunOS, is the leader. Experts estimate that 50 to 75 percentof today's ISP-based servers are Sun-based.

Of course, even within a given provider network, the parti cular purposeof a server--whether it's domain name services, e-mail, news feeds, shellaccount access, PPP/SLIP access, router/applications or Web hosting--canlead to differences in approach. Some ISPs make it a policy to ban the useof any off-the-shelf OS running stored programs on a transit network, sincethat network is so vulnerable to security breaches. Instead, those applicationsrun behind a firewall along with the administrative network. While Unixis the OS of choice, the box isn't always a workstation. Some ISPs run e-mailservices on Unix-based Macintoshes. Intel PCs are also used extensively.

Web hosting is expected to be provided on a variety of platforms, of course.Many ISPs are serving NT because of its growing base on corporate networks.Beta testing of Microsoft's own Internet Information Server on NT beganin late November, with shipments expected this quarter. Where demon performanceis needed, Silicon Graphics servers have often been the first choice, althoughsome ISPs grouse about SGI's l ack of software portability, skimpy managementcapabilities and high price. Nevertheless, SprintLink, one of the world'slargest backbone providers, relies extensively on SGI servers. Hewlett-Packard,with its reputation for price-performance, lays claim to more than halfof America Online's servers.

Lessons for Users What are some of the lessons ISP relianceon Unix brings to users building large intranets? A fundamental one is thatUnix's performance edge comes at the price of hiring a highly sophisticatedstaff. UUNET's O'Dell is among those bringing on more Intel Pentium platformsrunning a variety of Unix OSes, especially BSDI.

UUNET's Intel boxes are from Digital Equipment Corp. While such boxes oftenlet ISPs reduce costs as they ramp up, what O'Dell likes most about B SDIis its openness. "We can whack on these boxes and tune them to squeezeout every drop of performance." The downside, however, is that theirkeyboards and monitors make their operation in a central loca tion klugeyat best and have so far ruled out their use in lights-out centers.

What should users conclude about an ISP relying extensively on Unix PCs?On the upside, Dave Crocker, principal with Brandenburg Consulting, saysISPs that depend instead exclusively on Unix workstations may overburdentheir machines, rather than quickly bringing new Unix-based PCs online.One way for users to check out such a situation is to see if the ISP willoffer a per-port guarantee, such as no more than 10 users per port. Thedownside for PCs is the fact that some lack parity checking, he says. "Onereason people go for the workstation is that it's constructively mindless.The buyer has to be more informed and intelligent to get a PC platform thatis good." Analysts agree that some large ISPs have this knowledge,while many smaller ones can vary dramatically in their skill levels.

Getting TCP/IP Techies Another feature to pay attentionto in a server OS--especially for a Web server--is the acc ompanying TCP/IPimplementation in the server's Unix kernel. Different kernels support varyingnumbers of TCP/IP Control Blocks (TCBs). Internet Architecture Board memberand Network Computing columnist Robert Moskowitz warns that because theNetscape browser retrieves objects in parallel, rather than sequentially,it can tie up a larger number of TCBs. Each TCB must then wait a given interval--twominutes in many cases--to clear errors and once again be usable. Moskowitzbelieves that the popularization of Netscape means that more and more TCBsare used to download numerous small objects on a home page, elongating theuser's waiting period and causing more timeouts.

Unless Netscape and other browser vendors address the problem using newtechnologies like persistent connections, Moskowitz says it will be up toWeb providers to tune existing kernels, pick those supporting the most TCBsand impress on designers the importance of using maps versus individualobjects.

Does It Scale? ISPs also like Un ix's scalability. Sun President EdZander says NT "like everything else Microsoft does, is technicallyvery average, and they hope to get it to market based on sheer economics,volume and market size. NT doesn't scale well." Nigel Ball, directorof marketing for HP's General Systems Division, also boasts that NT "mightscale on two-CPU Intel systems, but we have 12-way RISC scaling-- ordersof magnitude better than NT."

Analysts say NT's chief asset will be the many inexpensive applicationsdeveloped for it as an Internet server. A Microsoft official also emphasizesNT's ease of deployment, management and application support. He also callsthe argument that NT doesn't scale "a red herring" because "99percent of the market needs four processors or less, and the eighth-largestInternet site in the country is a two or four-processor NT server"at Microsoft "that scales quite well."

Cisco Technical Lead, Tony Li, has his own assessment of the server's future: "the ISPs will continue to suffer scaling problems as they try to copewith exponential growth. The server that lets them roll their own, fix theirown problems, and provide stable, cost-effective performance will win. Iexpect some flavor of BSD just based on the programming environment. Hardwarewise,it's probably still a Pentium/Intel architecture."


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