Tricks & Traps: Ask Dr. Bob Your Windows NT Questions

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Bob Chronister

Windows NT Magazine, February 1999

Q: My domain administrator installed Internet Explorer (IE) 4.0 on my system and I didn't like it. When I tried to uninstall IE 4.0 from my system and rebooted my computer, my desktop was blank. What can I do?

A: IE 4.0 has an ongoing list of woes that range from running rdisk /s right after you upgrade, to the problem you are experiencing. The most likely cause of your problem is that you don't have administrator privileges. You must have administrator rights to install or uninstall IE, and these rights must be active the first time you boot after installing or uninstalling the software. Bite the bullet and ask your systems administrator for help.

Q: My company is planning to upgrade its leased Windows NT 3.51 machines to NT 4.0. Do you know of any specific problems we need to be aware of as the year 2000 approaches?

A: Your problem is the same problem many of us will face when upgrading to Windows 2000 (Win2K-formerly NT 5.0). You will have to deal with legacy hardware that NT 4.0 doesn't properly support. Check out the latest Hardware Compatibility List (HCL) on Microsoft's Web site at, and make certain that NT supports your hardware, which is unlikely if your machines are more than 3 years old.

Q: How can my company set up Microsoft Cluster Server (MSCS) without spending a lot of money on hardware?

A: Although I can't discern from your question why you want to use MSCS, I can't help but wonder why you want to economize on hardware when MSCS runs mission-critical applications. Microsoft has determined that serious use of MSCS demands high-end hardware. Some of the best systems I've seen for use with MSCS are from Compaq. These systems use SCSI-to-fibre channel converters and are impressive in performance and configurability. You simply set up Windows NT on internal, mirrored SCSI hard disks and install your other applications on external arrays in NT. You can use different RAID levels, as Screen 1 shows, on volumes and even dynamically resize the various volumes that you set up. I highly recommend these systems for any mission-critical setup.


Click here to view Screen 1 in a separate page.

Q: My company is creating a new Windows NT network, and we can't find any information about modem sharing. Does NT include this feature?

A: NT Server 4.0 and NT Workstation 4.0 don't include any built-in modem sharing capability, but the Small Business Server (SBS) version of NT does. If the network you're creating is small (i.e., 25 users or fewer), you might want to consider using SBS. If you're creating a larger network, you must use a third-party add-on utility for modem sharing such as LANSource Technologies' WINport modem pooling software.

Q: Do you know of an easy way to set up a home directory on a Windows NT server for my Windows 95 clients?

A: To create a home directory, you need to use a logon script with the net use x: /home command, where x is the drive letter that you want to map as the home share.

Q: On several occasions, I've repaired my Windows NT installation without using the Emergency Repair Disk (ERD). In all cases, the PC might not be able to boot properly if the PC boot files are corrupt or the Registry is damaged, which makes the ERD useless in these situations. However, I can always back up and restore my NT installation. If I want to take advantage of the ERD, I have to update the disk every time I change anything on my system, which isn't always practical. Therefore, what's the significance of an ERD?

A: I've seen installations where NT Setup can't find the corrupted or damaged NT installation. In such cases, you can't repair these types of installations without an ERD. At the same time, if you don't keep the ERD up-to-date, you can lose valuable program and setting changes you've made since the previous ERD update. On nonmission-critical systems, reinstalling and backing up a restored copy of the OS is a perfectly reasonable solution. For more information about the ERD, see "Ask Dr. Bob Your NT Questions," April 1998.

Q: How can I copy files and maintain the security attributes associated with the files under Windows NT?

A: The Microsoft Windows NT Server 4.0 Resource Kit contains the scopy.exe utility, which you can use to copy files and still maintain the associated security permissions from one drive to another under NT.

Q: I'm trying to determine the best way to measure the effectiveness of a caching RAID controller in Windows NT. I've run ZD Benchmark Operation's Winstone test, and the results were far from encouraging. Can you help me understand why RAID cache can help and how I can measure the results of adding cache?

A: To understand how cache on a RAID controller benefits NT, you need to understand how NT handles file caching and intensive hard disk I/O. NT allocates system memory for file caching and can check a hard disk's onboard cache. NT performs the latter when the OS's file cache fails (i.e., NT doesn't find the block in system RAM). If the hard disk's onboard cache doesn't contain the data (known as a cache-miss), the hard disk's actuator has to move to the track containing the data. This movement and retrieval can dramatically slow system performance.

NT's file caching is efficient in most applications where disk I/O is light (CPU-bound applications). When applications become increasingly bound to the hard disk, system idle time and frequency diminish. This situation results in NT's system cache (i.e., a page where the OS writes or modifies data but hasn't yet copied the sector to the hard disk) filling with dirty sectors. When the OS copies the data to the hard disk and flushes the sector from the system cache, the page is clean. Dirty sectors take up space that the OS could be using to store more recent data.

To help avoid dirty sectors, cache on a RAID coprocessed card can handle most of the data that NT's file caching misses. Because this I/O occurs at the speed of the PCI bus and not at the speed of the hard disk, all flushing and data transfers are more efficient than conventional transfers. The basic manner in which the transfers occur can even minimize disk thrashing seen with heavy I/O.

Testing the RAID card cache performance is complex. Most tests, including Winstone, are simply a serial battery of tests that runs each test sequentially and calculates a weighted average to create the final score. To add insult to injury, Winstone's design is biased against SCSI hardware (i.e., it favors IDE).

In a perfect world, all users would generate tests based on their individual environments. This statement is especially true when you consider the requirements for real-time video editing are far more demanding than for a user running Microsoft Word. The computer industry needs to pay closer attention to generating realistic benchmarks because users often don't have the time or the money to run the tests. I've been advocating the use of multiple benchmarks to represent system use. In the interim, your best bet is to time applications that you typically use. For example, you can run a set of batch files that start an application (or applications) and run specific disk I/O tasks. Compare your results with and without the RAID controller cache.

Q: Whenever I run DOS-based programs written in FoxPro, they use a tremendous amount of CPU time and all available memory. In addition, printing from these applications can be slow. If I print from within my DOS-based accounting software, the print job takes a long time to start printing. However, if I exit the DOS-based application immediately after I send the print command, the print job starts right away. My Windows-based applications don't exhibit this behavior, which makes me believe I can remedy this situation. Unfortunately, Microsoft no longer supports DOS. Can you help?

A: You can take several steps to fix your CPU, memory, and printer problems. Some DOS-based programs can perform an input loop that can use a lot of CPU time. Type

start /low

at the command prompt to start these programs in low-priority mode. (For a detailed explanation of the start command, type

start /? |more

at the command prompt.)

To fix the memory problem, create a Windows NT shortcut to the DOS-based FoxPro application and change the shortcut properties to limit the application's memory use. Continue to use the NT shortcut to launch the application.

Regarding the slow printer times, your applications are probably holding the printer connection open instead of closing it when they're finished. DOS-based applications used to maintain an open printer connection because they didn't need to share this resource with any other applications. You can force the printer connection to close by changing the printer's timeout value. Right-click the printer, select Properties, go to the Port settings, and decrease the timeout value.

Q: How does Windows NT handle DOS-based programs?

A: This question is complex. NT has trouble handling DOS-based applications because they're non-reentrant (i.e., nonmultitasking), and some of these programs want to directly access the hardware. Unfortunately, NT and DOS access hardware differently. Whereas NT defines a printer as the driver for the hardware, DOS defines the printer as the physical hardware. Therefore, any application that attempts to directly access the hardware in NT will probably fail. Applications that rely on their disk device drivers, directly address disk drives, or rely on their graphics device drivers to address the video will probably also fail under NT.

NT considers DOS to be part of a protected environmental subsystem. This subsystem consists of a set of APIs that let the environment run in NT. Specifically, the environment subsystem captures API calls and makes calls to native Win32 services that implement other calls that applications running under various environmental subsystems make. A user can start most of these environmental systems at the command prompt, which is a 32-bit character-based interface to NT and all its supported subsystems and file systems. The command prompt is becoming less popular, but it is very powerful. For example, you can perform the following functions from the command prompt:

  1. Start any NT (32-bit), Windows 3.x (16-bit), or DOS-based application

  2. Start applications at various priority levels

  3. Start any batch file with the extension .bat or .cmd

  4. Issue any NT command

  5. Administer or use network resources

  6. Copy information between applications, including applications running in different subsystems

Most users tend to overlook many of NT 4.0's command utilities, but they're powerful and functionally look similar to DOS 5.0 commands. One of the biggest differences is that NT 4.0 adds many new utilities, such as CACLS, which lets you display or modify access control lists (ACLs). Most of these utilities are 32 bit and return different error levels from their DOS counterparts. These commands run in native mode and don't call a Virtual DOS Machine (VDM). For a list and description of most of NT 4.0's command utilities, type Help at the NT command prompt. In addition to this list of utilities, you can type Deltree at the command prompt to delete a directory and its subdirectories and files.

VDMs are interesting threads that provide the environment in which DOS applications run under NT. This environment is similar to the environment that the Win3.x enhanced mode provides. Each DOS application runs in a 1MB virtual machine. By default, each DOS application has access to 1MB of extended memory, and you can emulate expanded (i.e., Expanded Memory Specification-EMS) memory for applications that require it. Each DOS application you run in NT has its own memory space. To make this isolated environment possible, NT uses a flat memory model rather than the classic 640KB model in DOS. In reality, each DOS application running under NT has about 620KB of conventional memory available. Programs running in a VDM can use almost all i386 instructions. Privileged instructions such as those that control paging won't work in a VDM.

So how do you configure a VDM? If you have an autoexec.bat file and config.sys file on your system root, you can add path and environmental variables to these files. NT will read these files on startup, append the path and environmental statements to the NT environment, and ignore everything else. When you launch a VDM, NT runs both the autoexec.nt and the config.nt for each VDM. The major difference between a DOS session and a VDM is the way in which the OS supplies EMS memory to an application. Keep in mind that in NT 4.0 you need to create a shortcut to the DOS application and use that shortcut's Properties page to control memory access. In truth, NT provides significant support for DOS-based programs.

Q: Is the rumor true that NTFS is nothing more than an enhanced High-Performance File System (HPFS)?

A: You can argue that NTFS is an updated version of HPFS. However, NTFS has numerous improvements that make it stand out from HPFS. These improvements don't affect most standalone PCs, but they can be important for some large business environments. For example, you can install NTFS on any drive (including CD-ROM drives, 3.5" disk drives, and removable drives), but you can install HPFS on only fixed hard disks. NTFS has built-in file compression to compress files as needed, and HPFS doesn't support this feature. NTFS has built-in security support to prevent users from accessing files, and HPFS doesn't have this feature. Finally, NTFS lets you use clusters and achieve the best performance possible; HPFS doesn't support clusters.

Q: I recently tried to use the PrntScrn key to print the screen of a Compaq system that shares a monitor with several other systems. Unfortunately, the Compaq system uses the PrntScrn key to switch the monitor from one system to another. How can I print the screen on this system?

A: You can try using the Alt key in combination with the PrntScrn key. This approach has worked for me on Compaq systems.

Q: I'm trying to capture screen shots during the Windows NT setup process. However, the system reboots several times when I press the PrntScrn key. What can I do?

A: Simply put, you can't use the PrntScrn key during the text-based phase of NT Setup. The system might reboot or display an emm386 error message. However, when you install NT from DOS or Windows 95 using winnt.exe, the software doesn't disable special input keys such as the PrntScrn key in case you terminate NT Setup and return to your OS.

Q: Our Windows NT network connects to the Internet via an ISDN router that lets Microsoft Exchange Server send and receive Internet email through our Internet Service Provider (ISP) and lets our network users access the Web. The network obtains an IP address for each user from the NT server via Dynamic Host Configuration Protocol (DHCP-our ISP gave us 16 fixed IP addresses). What kind of security measures can we take to protect ourselves from external attacks over the Internet?

A: In your current configuration, you're wide open to intrusion. By all means, I suggest that you get a firewall to isolate your network systems from snoopers and disaster. For information on implementing some interim security until you can put a firewall in place, see Douglas Toombs, "Poor Man's Firewall," December 1998.

Q: Do you know where I can find a comprehensive list of all Windows NT event log Event IDs?

A: The Microsoft Windows NT Server 4.0 Resource Kit Supplement 2 comes with a Microsoft Access database file with all the Event IDs.

Q: I'm using Windows NT Workstation 4.0, and the Internet dialer keeps popping up every 10 minutes. I've checked all the system settings, but I can't figure out what's causing the system to redial and how I can control the redialing. Can you help?

A: Click Start, go to Accessories, and select Dial-Up Networking. Click More from the Dial-Up Networking dialog box, and select User preferences from the drop-down menu. Deselect the check box in the top part of the window for enabling auto-dial.

Q: I can't establish a dial-up Internet connection on my Windows NT machine. I used the Internet Explorer (IE) Connection Wizard to set up the Internet dialer and TCP/IP. When I start IE 4.0, my modem dials and Point-to-Point Protocol (PPP) negotiation succeeds, but the Internet connection is dead. If I enter a URL in IE 4.0, the software tries to find the Web address but eventually times out and displays an error message saying that it can't find the appropriate site.

When I manually select Dial-Up Networking (DUN) or when I try to download mail from my Internet Service Provider (ISP), the same problem occurs. The Outlook Express application will start, but it won't download my email from the Post Office Protocol (POP) server. When I run NETSTAT -a, I receive the message No Response (i.e., no IP addresses are listed). When I ping a known site, I also receive the message No Response (i.e., no address found). What's going on?

A: I suspect you're experiencing a Domain Name System (DNS)-related problem. You need to enter your ISP IP addresses on your system. Check the ISP setup for DNS servers in the DUN properties.

About the Author

Bob Chronister is a contributing editor for Windows NT Magazine and president of Chronister Consultants in Mobile, Alabama. He is coauthor of Windows NT Backup and Recovery (Osborne/McGraw-Hill). You can reach him at

Send your tips and questions to Windows NT Magazine. You can also visit Bob Chronister's online Tricks & Traps at

The above article is courtesy of Windows NT Magazine.

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