Underlying XP Architecture

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Windows XP represents the death of DOS, at least on any Windows platform. For the first time, all versions of Windows (including the server, workstation and home PC versions) are running on the same kernel. This simplifies administration, particularly because Microsoft built the new operating system on the Windows 2000 kernel, its most stable kernel yet, which means fewer blue screens and reboots and fewer calls to the help desk than from clients running NT 4.0 or, worse, Windows 95, 98, or Me.

Windows XP, therefore, has several key advantages: (1) fewer crashes, (2) one basic code for all PCs, (3) compatibility with over 90% of the 1500 most popular Windows applications, and (4) support for over 12,000 devices. Microsoft's newest operating system also offers such features as a built-in firewall, CD Writer software, Windows Media Player, Movie Maker, an extremely limited defragmenter that functions poorly in the enterprise, and System Restore.

System Restore addresses the subject of those multiple error messages that plague NT. I used to receive two per hour due to an incompatibility with Norton Antivirus, as well as several alerts after startup for various reasons. System Restore makes it possible to remove this hassle by reverting to a previous system state if a new application creates errors. Essentially, it is a combination of file system filter driver and user-mode services that provides a way to revert to an earlier configuration.

Another recovery function built into XP protects against the installation of driver updates that create problems. A hardware installation wizard backs up replaced drivers so that system restore is effectively made available if the driver update goes badly. A Last Known Good recovery option accessed through the boot menu allows users to revert to the previous drivers.

The defragmentation APIs within Windows XP have also been revised. For some years NT file systems have used exposed APIs that allow the querying of files in order to defragment files. The NT APIs do not address directories, the Master File Table (MFT), or paging files; in Windows 2000, they do not address the MFT or paging files. Now, with XP, only the paging file is untouched by these APIs so the results of regular defragmentation are more thorough than ever when using a third-party defragmenter.

Another significant shift in Windows XP is support for 64-bit computing. The 64-bit version of XP runs on the Intel Itanium processor. The IA-64 platform offers improvements in terms of floating-point performance to speed up activities such as three-dimensional modeling, human genome analysis, and special effects. Because it can access up to 16 TB of RAM, entire databases can reside in memory at access speeds 100 times greater than disk I/O.

Unfortunately, IA-64 lacks supporting applications at the moment. Computer Associates, BMC, SAP, J.D. Edwards, IBM, SAS Institute, VERITAS, and others have ported 32-bit applications to the new platform. Early pioneers include Wells Fargo's use of a 64-bit version of a SAS Institute database. Some of the tables used for quantitative modeling in this application have 600 million observations and performance is much better on a 64-bit platform.

Note, however, that many of these enhancements are available only on XP Pro, not the consumer-oriented XP Home version, which has no place in the enterprise. Professional extras include a backup utility, Remote Desktop (which allows administrators to access PCs remotely and users to pull up files while out of the office), dual processor support, Access Control (which restricts access to selected shared files, applications, and resources), roaming profiles, client-side caching, dynamic disks, SNMP, Intellimirror, and IIS. Additionally, XP Pro has a built-in fax utility, allows for AD log-ons, and features the Encrypting File System (EFS).

Security, in fact, has been given considerable attention in XP Pro. It contains several security improvements not available in Windows 2000 such as multiuser support for EFS. Based on public-key encryption, EFS encrypts and decrypts files using randomly generated keys. This enables multiple users to access encrypted files. The inclusion of security features, however, has not transformed XP into the desktop Fort Knox. Holes that make it possible to take over XP at the system level have been discovered by hackers. While patches have been issued, third-party security products should be relied upon in an enterprise environment.

On top of security shortcomings are several additional points to be aware of to minimize user complaints. Microsoft could perhaps be accused of optimism in its minimum system requirements: 233 MHz CPU, 128 MB of RAM (64 MB minimum is supposed to be supported, with the warning that this setup may limit performance and some features), and 1.5 GB of available hard disk space. When it comes to memory, XP surely needs a lot of it. Microsoft recommends 128 MB RAM minimum, but this is not really enough. One of my machines has 128 MB RAM and it rarely has more than 14% physical memory available. As a result, the paging file is under heavy use — constant usage at 85 percent or greater, even with little running. It is advised, then, to load typical workstations with at least 256 MB RAM and far more for high-end workstation users.

A 233-MHz CPU will not work with XP, as even my old 400-MHz machine could not take the load. Although a 1-GHz CPU was a big improvement, a few months down the line, CPU utilization was often topped out. So, 2 GHz is probably the minimum for XP. A 1-GHz CPU may be enough for some users, but it may be better not to load XP on older machines and to delay the XP installation until the lower powered desktops are ready to be replaced. For high-end machines running graphics-intensive applications or which are used for such things as software development, a faster CPU should be considered an absolute must.

When it comes to hard disk space, XP is a monster. The operating system alone takes up most of the 1.5 GB of recommended available disk space. So, if users have old systems with small hard drives in the range of 4 GB or below, their choices are simple: Forget about XP, upgrade the hard drives, or purchase new machines. Realistically, a 10-GB drive is the minimum, and with hard disk prices so low 20 GB assures that user complaints about running out of space will be few and far between.

So, is XP Pro for you and your many users? If Windows 2000 is already on every desktop, possibly not. The differences between XP and Windows 2000 are relatively minor in comparison with XP versus Windows NT or 9x. With budgets being tight, it is likely that Windows 2000 desktops will stay right where they are for another year or two. For everybody else, though, there are plenty of reasons to move to XP. Help desk operations will benefit enormously from the stability, reliability, and remote management features of XP. User calls should be less frequent, and those that come in can be dealt with remotely much more easily.

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