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Part I
Introduction

Chapter 1
Overview Of Windows NT Architecture

•  Windows NT System Design
•  The New Technology File System
•  Understanding Fault Tolerant Features Of Windows NT Server
•  Tools For Centralized Administration

This chapter introduces the features of Windows NT Server, explains Microsoft’s buzzwords associated with Windows NT Server, and prepares you for the following chapters, where we will work with Windows NT Server. If you are already familiar with NT’s features, you may want to skip this chapter and move on to Chapter 2, “Installing Windows NT Server.” For those of you who have never worked with Windows NT Server, this chapter has a lot to offer. In this chapter, you will learn just why Windows NT Server is one of the best network file and print servers available in today’s market.

The Windows NT Design

The current version of Windows NT Server (version 4.0) includes some enhancements, which we will discuss a bit later in this chapter, but the basic component model has stayed the same in each release. If you have read any of Microsoft’s literature about Windows NT Server, you’ve probably wondered just what was meant by the scattering of various buzzwords and how the buzzword-laced text related to your day-to-day activities as a network administrator. Well, that’s what we are going to look at here. While I have not included all the buzzwords, I have included the ones that I think will make a difference in your life. And these are:

•  Robust—When you hear this word used in conjunction with Windows NT, it simply means that Windows NT is designed to not crash when an application fails in some fashion. NT accomplishes this by utilizing two specific features. The first feature is that all applications execute in their own address space (with the exception of 16-bit Windows applications, although this too can be user selected so that even 16-bit applications execute in separate address spaces). Secondly, operating system components are protected-mode components. Windows NT does not rely on any real-mode components (a real-mode application can access any memory or I/O location arbitrarily, which can lead to a system crash) to interact with your computer hardware (as Windows 3.x does). This is both good and bad in some ways, but it’s the price we have to pay for an operating system that will not crash easily.

TIP:  Because Windows NT does not use the BIOS (a real-mode component) to access the hard disk controller, not all hard disk controllers will work with NT. If you want your unsupported hard disk and controller to work with NT, you will need a Windows NT device driver to support it. And because NT prevents applications from accessing the hardware directly, not all MS-DOS and Windows 3.x, or Windows 95 applications will work when running under NT. In this particular case, a virtual device driver, or VDD, is required to support the hardware access.
•  Fault Tolerant—This particular feature is so important that I cover it in more detail in a later section in this chapter. For now, you can just consider fault tolerant to mean that Windows NT Server provides the means to protect your data and keep the server running if at all possible. NT does this by detecting various software and hardware failures. If a failure is detected, then the redundant hardware will be utilized to continue to provide access to your network server by your network clients.
•  Secure—The good news about security is that Windows NT does provide reliable methods to limit access to any computer resource. This includes not only access to the server and your data, but also access from one application to another application. There are two aspects to consider for this item. The first aspect is related to limiting access to the network file server’s shared resources and the server itself. This is accomplished through user identifications (user IDs) and passwords, or local or group identifiers (these topics are covered in more detail in this chapter, in the section titled Centralized Administration). The second aspect is related to keeping your data secure from unauthorized access and is covered later in this chapter, in the section titled The New Technology File System (NTFS).
•  Scalable—When people mention scalability and Windows NT Server in the same breath, it generally refers to providing additional performance. Most people only consider adding additional resources, such as another CPU or disk channel (a disk controller and disk drives). But scalability really refers to the ability of Windows NT to execute on different hardware platforms, such as the NEC MIPS processor, the DEC Alpha processor, and the IBM/Motorola PowerPC processor. Each of these platforms can provide additional performance gains over Intel processors.

Note:  Microsoft has stopped development efforts for the PowerPC and MIPS processors. This means these processor platforms are dead ends because there will be no further service packs (bug fixes), and future versions of Windows NT Server will not operate on these platforms.
•  Symmetric Multiprocessing (SMP)—Windows NT’s internal design utilizes a symmetric processing model, which simply means that all processors can access system resources (memory, interrupts, and so forth) and that any process/thread can execute on any processor. This is quite different from an asynchronous multiprocessing (AMP) model, where one processor is responsible for the operating system functionality and another processor is responsible for executing applications. With Windows NT, any process can execute on any processor providing the ability to make more efficient use of available processor resources.
•  Multithreading—A thread is the minimum executable resource in Windows NT. The difference between a thread and a process is that a process is the container for an address space, while a thread executes within that address space. A process by itself is not executable. It is the thread that is scheduled and executed. What is unique about threads is that a single process can have more than one thread of execution. For instance, a multithreaded application can have one thread for user input (keyboard and mouse), another for printing, and another for file access. When you print a file, or even save a file, these threads run in the background, while the user thread runs in the foreground. So, as far as you are concerned, your application continues to respond to your input, and you never see the hourglass as you do in Windows 3.x and Windows 95.
•  Compatible—This refers to the ability to execute your legacy applications. These applications include your MS-DOS, 16-bit Windows, and OS/2 character-mode applications. It also includes the ability to execute recompiled POSIX 1003.1 compliant applications. Each of these applications executes in a different environmental subsystem. Subsystems are discussed a bit later in the following section titled “The Windows NT System Design Model.”
•  Integratable—This is one of the joys when working with Windows NT Server, because it means that you do not have to tear up your existing network. Instead, Windows NT Server can happily coexist with your Unix, Novell, Banyan, and LAN Manager networks. NT also includes the ability to migrate your existing Novell and LAN Manager networks to Windows NT networks over a period of time or to emulate an existing Novell server.

Once the techno-babble has been stripped away and the buzzwords translated into plain English, the strengths of Windows NT Server become more self-evident. But there is more to Windows NT Server than the basic feature set can explain, so let’s move on to a model illustrating the Windows NT system design.


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