Build Your Own Dual-Processor Server

Multiprocessing power without the expense

Before you read on, heed this warning: Do not try to assemble your ownmission-critical server. You are better off purchasing a system from amainstream hardware vendor to run mission-critical applications. Vendors can address your support, repair, and parts needs for systems you purchase from them, but you're responsible for providing support, repair, and parts for a server you build. Most organizations don't want to risk running essential applications on home-built systems.

Despite this warning, you have plenty of opportunities to roll up your sleeves and build a server. Non-production test systems; servers that aren't mission-critical, such as print servers; and even some infrastructure servers, such as Dynamic Host Configuration Protocol (DHCP) or routing servers, can be candidates for low-cost, build-it-yourself platforms.

Building your own dual-processor Windows NT server costs about the same as buying a high-end single-processor machine, plus a couple hundred dollars forthe second CPU. You need the same Error-Correcting Code (ECC) RAM, SCSI disksubsystem, video subsystem, and incidentals (including the case, keyboard, andmouse) for single- and dual-processor systems. If you're upgrading a systemrather than building the server from scratch, you can salvage many of thesecomponents from the existing machine. The only components you definitely mustbuy are a new motherboard and at least one CPU.

Mother of All Choices
Multiprocessor motherboards are similar to single-processor motherboards,but multiprocessor motherboards include additional circuitry to supportsymmetric multiprocessing (SMP) and an additional socket for a second CPU.Different SMP motherboards offer a variety of extras, such as onboard SCSIadapters, video adapters, and sound cards.

Before you select extra features for your motherboard, you must decidewhether you want to use Pentium, Pentium Pro, or Pentium II processors. You mustchoose Pentium-class CPUs­ Advanced Micro Devices (AMD) and Cyrix CPUswon'twork on a multiprocessor NT system.

Pentium-class processors can use Advanced Programming Interrupt Controller(APIC), Intel's chipset standard for SMP technology. AMD and Cyrix processorsuse a different standard, OpenPIC, which NT doesn't currently support. Table 1,page 82, lists several multiprocessor Pentium, Pentium Pro, and Pentium IImotherboards you can choose from and includes each motherboard's feature set.

If you want to upgrade a single-Pentium machine, your cheapest option is to upgrade to a dual-Pentium system. Many mail-order establishments sell200MHz Pentium CPUs for less than $200 and dual-Pentium motherboards cost only marginally more than single-Pentium motherboards. Without memory, onboard SCSI cards or NICs, or other extra components, dual-Pentium mother-boards range in price from $175 to $300.

If you want to maximize your CPU power, you'll be interested in the PentiumII processor. This solution is expensive. The fastest Pentium II CPUs (333MHz)cost more than $700 each from mail-order firms, and at least $800 from localsuppliers. In addition, the Pentium II platform currently lacks scalability;only two CPUs fit on multiprocessor Pentium II motherboards. Don't build adual-Pentium II system if you might need to add more CPUs to your server withinthe foreseeable future.

If you want a reasonable compromise between slow, inexpensive Pentiumprocessors and fast, high-cost Pentium II processors, you can build amulti-Pentium Pro server. The fastest Pentium Pro processor is 200MHz, with a512KB Level 2 cache. Independent lab tests have demonstrated that 200MHz PentiumPro processors perform application- and file-server functions only marginally slower than 300MHz Pentium II CPUs, presumably because of the Pentium Pro processor's faster Level 2 cache. You can purchase a 200MHz Pentium Pro processor with a 256KB Level 2 cache for about $500. The same CPU with a 512KB Level 2 cache costs roughly $200 more.

The disadvantage of implementing a Pentium Pro SMP solution is that Intelhas announced it will discontinue Pentium Pro processor production, and manymotherboard vendors are phasing out production of Pentium Pro motherboards.You'll probably have trouble upgrading a dual-Pentium Pro system to include moreprocessors in the future. In addition, you might not be able to replace existingparts, so a motherboard failure could leave you stuck with two or more orphanedCPUs.

After you decide which CPU platform you want to use, you need to evaluatethe features available on motherboards designed for that platform. Somemotherboards include a built-in VGA port for connecting a monitor. Manymotherboards include an onboard Adaptec SCSI controller for connecting SCSIdevices internally. In addition, some high-end Pentium and Pentium Promotherboards provide multiprocessing power through a backplane anddaughterboard. The daughterboard contains the CPU circuitry, so the next timeyou want to upgrade your system, you just replace the daughterboard. Thebackplane is similar to a typical motherboard, except that it has a specialexpansion slot where the daughterboard plugs in. The only problem with thisconfiguration is that the backplane's expansion slot for the daughterboard mightcramp your PCI, EISA, or Accelerated Graphics Port (AGP) expansion slots orreduce the number of expansion slots the backplane can hold.

Evaluate the motherboards available for the platform you're considering,and determine which features are important to you. Each feature adds value, butit also increases the motherboard's price, and it might require you to purchaseadditional hardware. If you don't need a feature, you're better off buying amotherboard without it.

Extra Hardware
To upgrade a system from one CPU to two CPUs, you might need to installreplacement RAM. If you are running a single-processor NT server, you probablyhave 72-pin Enhanced Data Output (EDO) SIMMs, or perhaps 72-pin fast-page-modeSIMMs with parity. If the new server's reliability is paramount, you'll requireECC SIMMs. RAM prices fluctuate daily, but you can estimate your RAM costs basedon the current price for a 64MB ECC SIMM, $140.

You might need to upgrade your RAM even if you don't require ECC SIMMs.Most dual-processor Pentium II motherboards use Synchronous DRAM (SDRAM) orDIMMs (168-pin memory chips that resemble SIMMs but are longer). You'll pay onlya few dollars more for one of these chips than for a 72-pin SIMM with the samememory capacity.

In addition, if you upgrade to a Pentium II system, you'll probably have toreplace your system case. Most dual-Pentium II systems use the new ATXfootprint. ATX is not compatible with existing Pentium cases; therefore, you'llneed to spend another $100 on a case to upgrade to a dual-Pentium II system.

This New System
Physically putting together a dual-processor system is no different thanconstructing a single-processor system. You open the case, install themotherboard, adjust jumper settings, install the CPUs, install the drives andother peripheral cards, and put everything back together. To measure howdifficult building an SMP server is, I threw on a plaid wool shirt, broke out mytoolkit, and became the Norm Abram of the SMP server world.

I contacted a local hardware distributor with whom I have a good workingrelationship. A distributor can provide you with information about whichmotherboards are on the market, the features each motherboard offers, and whichserver components you need to upgrade. I contacted seven motherboardmanufacturers that my distributor recommended and obtained product samples tobuild my server. ASUSTeK (ASUS), M Technology, American Megatrends (AMI),Micronics Computers, Tyan Computer, SUPERMICRO Computer, and EPoX Computerprovided dual-Pentium II motherboards. Micronics and Tyan also provideddual-Pentium Pro motherboards. The Micronics, SUPERMICRO, and ASUS motherboardswere the easiest to work with, in that order.

I gutted an Acer America 133MHz Pentium clone. I salvaged the unit's 1MBVGA card, SMC ISA Ethernet card, Adaptec 2940 SCSI disk controller, 3.5"drive, and Quantum 4GB hard disk. I replaced the unit's 4X CD-ROM drive with anew 24X CD-ROM drive. I purchased two 300MHz Pentium II CPUs and 128MB in SDRAM.I also bought a case to accommodate the ATX form factor.

I assembled my test system using the Micronics dual-Pentium II motherboard.During the assembly, I faced a few problems. I accidentally destroyed my 3.5"drive, so I had to purchase another one. My 1MB video card flickered noticeablyon the new system, so I upgraded to a Matrox Mystique 220, which solved theproblem.

I added a Sound Blaster-compatible sound card, which requires IRQ 5 or IRQ10. The motherboard's Universal Serial Bus (USB) ports require IRQ 5, so thesound card consumed IRQ 10. Unfortunately, my Ethernet card requires IRQ 10, somy network card wouldn't work after I installed the sound card. I had to replacethe SMC Ethernet card with a new PCI Ethernet combo card that uses the upperIRQs. The entire upgrade, including a couple trips to the distributor foradditional parts, took 6 hours.

Reboot and Go?
Throughout the upgrade process, NT never choked. After my initial upgrade, Ireplaced the Micronics motherboard with each of my other test motherboards. Ihad problems booting four of the motherboards, but I resolved these problems byadjusting CMOS settings (e.g., I disabled the onboard SCSI controller andmanually modified the PCI cards' IRQ assignments). After I switched video cardsand network drivers and adjusted CMOS settings, each motherboard booted NTServer 4.0 without a problem.

Nevertheless, I had to sort out my new server's NT configuration. If youcreate a multiprocessor NT server from scratch, you must perform a full NTinstallation so that you won't encounter any problems. However, if you upgradean existing NT server from one processor to two or more processors, you'll facea configuration problem.

When I installed NT on the single-processor server I upgraded for thistest, NT recognized that I wasn't running an SMP platform and automaticallyinstalled the single-processor NT kernel configuration. My hardware upgradesdidn't change the NT operating system (OS), so when I rebooted the server withthe new motherboard and second processor, NT didn't recognize the secondprocessor.

I could have reinstalled NT to correct this problem, but instead I used theuptomp.exe utility in Microsoft Windows NT Server 4.0 Resource Kit.UPTOMP upgrades a server's OS from a single-processor to a multiprocessorconfiguration. (The utility is in the Config section of the NT Server 4.0resource kit. You can also find it in the I386Config directory of MicrosoftWindows NT Server 3.51 Resource Kit.) A text file in the resource kitexplains how to use the utility. UPTOMP is simple, but you must be careful whenyou run it. You must provide UPTOMP with a path to the hardware abstractionlayer (HAL) you want to install. If the path is wrong or you select the wrongHAL, the mistake might render your system unbootable.

Fantastic Cost Savings
My upgrade cost more than I expected. The 24X CD-ROM drive cost $90, and thenew 3.5" drive, Ethernet card, video card, and sound card added roughly$500 to the test price. Still, I built my dual-processor NT server for less than$3000.

You might be able to build a dual-300MHz Pentium II system for even less.You can reduce your costs dramatically by salvaging existing system components,including video cards, hard disks, 3.5" drives, network cards, and soundcards. My system's motherboard, CPUs, case, and RAM cost only $2320 (as Table 2shows, page 83). You can reduce your costs even further by purchasing adual-processor motherboard without extras such as onboard RAID and SCSIcontrollers.

Transforming a server you already have into a high-powered SMP machine willsave you money over buying a new server. You can upgrade to dual 300MHz PentiumII processors for less than $2500 and upgrade to a dual-200MHz Pentium Proplatform for slightly less. Either option saves you money. SMP servers frommajor manufacturers can cost $10,000 or more, so $2500 for a major systemupgrade is money well spent.