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Everyone wants his or her network server to perform as well as possible and to be as easy to manage as possible. By choosing to use Windows NT Server as your network operating system, you are already heading down the right track. Windows NT Server is designed to perform well by making intelligent configuration decisions. Windows NT Server basically tunes itself for optimal performance. This does not mean that all you need to do is pick a computer, install Windows NT Server on it, and expect to have a super-server. To get the most out of Windows NT Server, you need to make informed hardware choices. The following sections explore many possible choices and explain how your choices affect the performance of your server.
Windows NT Server has the ability to execute on several processor platforms. These platforms include the Intel processor line, which is a CISC (Complex Instruction Set Computer) processor, and several RISC (Reduced Instruction Set Computer) processors. You may currently use the MIPS, Alpha, or PowerPC RISC processors. Although, the PowerPC and MIPS processors seem to be in decline with Microsoft, and further development for these platforms has been discontinued. This means choosing either the PowerPC or MIPS processor is not a good choice for your next server.
The primary difference between a RISC processor and the Intel processor, aside from the purchase price, is twofold. First, the Intel processor is the only CPU that can execute OS/2 16-bit character-mode applications or be used to boot MS-DOS in a dual-boot configuration. If this is not a real issue for you, then you can ignore these options and just consider the second difference. Pure performance. Depending on the RISC processor line you choose and the clock speed of the processor, one of these platforms may perform better for you than the Intel processor. But, it is getting very difficult to make a recommendation for a RISC processor over the Intel processor line, because the Intel processor line keeps improving. Furthermore, the gap between CISC and RISC processors is decreasing with each new Intel processor.
Intel has been utilizing many RISC constructs in its new processors (such as the Pentium Pro) to improve the overall performance of the processor. Each new generation of processors provided by Intel ups the ante in sheer performance. At a minimum, I recommend that you use a Pentium 133MHz processor for your server. If you can afford it, use a Pentium MMX processor or, better yet, a Pentium Pro 200MHz processor. Currently, the only processor I would consider as an alternative to the Intel processor is the Digital Equipment Corporation (DEC) Alpha processor. This processor is available with clock speeds up to 500MHz. A server using this processor makes a very fast application server (an SQL Server, for example). I also expect DEC to continue its partnership with Microsoft and continue to provide development support for Windows NT.
When you consider that the primary job of a server is to share resources, such as file and printer resources, then the speed of the processor is not always the most relevant issue. Processor performance is a concern because Windows NT is more processor-intensive than other network operating systems, but that is not the most relevant issue. Instead, you should be more concerned with the I/O expansion bus, the memory subsystem, and the peripherals you choose because these often have more of an impact on overall network performance. One of the best insurance gambles you can make, however, is to purchase a computer system that supports more than one processor.
Windows NT Server supports the symmetric multiprocessing model (SMP). This means that you can use more than one processor—up to four with the standard version of Windows NT Server or up to thirty-two with an OEM version of Windows NT Server—on your computer simultaneously. Adding an additional processor can make a significant difference in network throughput or an application server’s performance (such as an SQL Server). This performance increase, however, is not quite twofold for a dual-processor system. And as you increase the number of processors, this performance ratio decreases. As it stands, four processors give the greatest multiprocessor benefit on standard Intel (Pentium) platforms. This is because most motherboard manufacturers utilize the Intel multiprocessor support chipset, which only supports four processors. Above that, it depends on the proprietary design of the system motherboard.
One interesting key I’ve found in the registry is the key that specifies how many processors are supported on a particular multiprocessor Hardware Abstraction Layer (HAL). If you look in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\ Control\SessionManager, you will find the value RegisteredProcessors. This entry normally has a maximum setting of 4 for Windows NT Server or 2 for Windows NT Workstation. You can increase this value to support additional processors and thereby increase performance on some computer systems. I say some computer systems because this tip will only work if your HAL can support the additional processors. The performance increase is also based on the architecture of the particular platform. Some platforms will perform better than others, even if they have the same number of processors.
The problem with multiple processors is that the Windows NT design model requires that all processors have equal access to all system resources. That is what the symmetric multiprocessing model defines. This means that the overhead involved in synchronizing access to hardware resources (such as an I/O port on a SCSI controller) increases as you add additional processors. Problems with cache management can also cause grief, as each processor generally has its own secondary cache. As a thread is moved from one processor to another, the cache must be flushed in order to ensure the integrity of system memory. All of these little problems begin to build, until adding additional processors no longer increases performance or, at best, only increases performance by a small fraction.
After you have determined which processor platform (and how many processors) to use on your server, you need to choose an I/O expansion bus.
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