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Migrating to Windows NT 4.0
Last Updated 2/3/2009 3:42:58 PM
Abstract
Although Windows NT 4.0 is a highly self-optimizing system you can take certain steps to make it perform with even greater efficiency. This chapter includes recommendations for optimizing your Windows NT system, including tips on system hardware, configurations, and maintenance.
RECOMMENDED HARDWARE FOR WINDOWS NT 4.0
In general, the better your hardware, the happier you’ll be with Windows NT 4.0’s performance. Certain areas are especially important to consider when you specify or purchase hardware for a Windows NT computer.
Memory — and Lots of It
Sufficient RAM is absolutely critical to the efficient operation of Windows NT. Although Windows NT requires more memory than other Windows products, such as Windows 95 and Windows 3.x, it uses memory to improve overall system performance in ways that these other operating systems cannot. One of the easiest ways to bring a Windows NT system (or any system, for that matter) to its knees is to run it on a machine with insufficient RAM. When this situation occurs, the system is forced to use virtual memory provided by the Windows NT Paging File, which is exponentially slower. You’ll know when your RAM is insufficient by the increased disk activity that occurs when the system begins swapping pages frequently with the Paging File.
For optimal performance, put at least 32 MB of RAM on any Windows NT Workstation computer. If the system will experience heavy application demands, such as large engineering, graphics, or CAD applications, or the multitasking of a large number of programs, consider adding even more RAM.
On a computer that runs Windows NT Server and functions as a file and print server, start with at least 48 MB of RAM. Add more memory if the computer serves many users or runs large programs, such as Microsoft Exchange Server or the Internet Information Server (IIS). On these systems, consider 64 MB a minimum quantity for consistently acceptable performance.
Remember also to monitor your memory load index and Paging File usage using the tools available in Windows NT 4.0, including the Windows NT Diagnostics Utility and the Performance Monitor Utility.
Hard Disks
Windows NT was practically built for Small Computer System Interface (SCSI) hard disk subsystems. SCSI’s low CPU utilization, device independence, bus mastering capabilities, and high data transfer rates all lend themselves to use in the Windows NT environment. For optimal speed, SCSI (and its sibling standards, Fast SCSI-2, Fast/Wide SCSI-2, SCSI-3, Ultra SCSI, and so on) is the only type of hard disk you should use on your Windows NT 4.0 system. Although you can save a few dollars buying cheaper IDE/EIDE drives, the decrease in performance caused by the higher CPU overhead and lower transfer rates typical of EIDE drives will outweigh your savings.
Because EIDE drives require the host computer’s CPU to administer each drive I/O operation, EIDE drags down system performance by stealing CPU cycles away from other running processes. SCSI controllers, on the other hand, support several technologies that alleviate this burden from the CPU and increase the overall system speed. SCSI host adapters are intelligent and — along with SCSI devices — are capable of carrying out I/O operations with only minimal attention from the host CPU. SCSI’s support for up to seven devices (15 with some controllers) per SCSI adapter also means you’ll be able to leverage your SCSI controller purchase and add additional SCSI-based devices (e.g., scanners, tape drives, CD-ROM drives, rewritable optical drives, additional hard drives) later on.
Video, Disk, and Network Adapters
You need to use video, disk-controller, and network adapters that work on high-speed buses such as the EISA, VLB, and PCI buses. Often video and disk subsystems are the two subsystems most heavily taxed in graphical operating system environments, and the higher transfer rates and wider data paths (32-bit or even 64-bit) of these buses let these components run more quickly. The PCI bus is especially suited to the NT environment because it provides the highest data transfer rates and lowest CPU utilization of the bus technologies mentioned.
CPU Platforms
When you choose a CPU platform for your Windows NT system, you have to consider several factors. Intel-based systems (486, Pentium, and Pentium Pro) are by far the most popular, and the Pentium Pro is an especially good choice for Windows NT because of its 32-bit code optimization techniques. On the other hand, many RISC-based systems offer some significant speed advantages that you shouldn’t ignore. The price of RISC systems, such as those built on the DEC Alpha and PowerPC CPUs, has dropped recently. In some cases, you can buy a RISC-based computer that has one-and-a-half to two times the raw computing power of a comparably priced Intel-based system.
However, factors other than price and power may influence your decision. Because all applications have to be compiled for the hardware platform on which they run, and because most applications are only available in Intel x86 architecture versions, you may end up running many of your applications through Windows NT’s Intel emulation on a RISC-based Windows NT system. Your system, therefore, will run more slowly because it will need to constantly convert Intel-based CPU instructions to the native instructions used by the system’s RISC processor.
If your applications are mostly mainstream products or general business applications, your best bet is probably an Intel-based system because of its dominance in the software applications market. However, if you will be using your Windows NT system for high-end graphics, CAD, animation, engineering, or similar applications, you should consider a RISC-based platform, because it can provide the speed these applications demand. Application servers, such as database servers or Internet servers, are also good candidates for RISC-based platforms.
OPTIMIZING MEMORY
As you already know, memory is the most important resource for Windows NT 4.0. Therefore, you need to manage Windows NT’s memory efficiently, ensuring that system memory is not wasted on nonessential functions.
Remove or Disable Nonessential Services
To begin optimizing memory usage, consult the list of services running on your Windows NT 4.0 system and determine whether any of the installed services are unnecessary or unused. Remove any extraneous service (by setting the startup type to manual or disabled in the Control Panel’s Services applet, or by removing a network-related service in the Control Panel’s Network applet) to free up memory for the operating system and for user applications. When you analyze the list of network services, look for items such as unnecessary network clients and protocols, as well as any services listed in the Services applet that aren’t needed in your environment.
You can also reduce memory usage by minimizing the number of 16-bit applications you run in a separate memory space. Although running 16-bit applications this way provides greater stability and protection for the application, it takes its toll on memory because each application must receive a dedicated virtual DOS machine (VDM) and a copy of all environment information. Sixteen-bit applications running in a single shared VDM, on the other hand, share environment information and use memory more efficiently. Only notoriously ill-behaved 16-bit applications or those that are greedy for system resources should be run in separate memory spaces.
OPTIMIZING THE PAGING FILE
The Paging File created in the Control Panel’s System applet will be used as virtual memory when the system needs to swap memory pages out to disk. The Paging File is an important part of Windows NT’s operation, even on systems with generous amounts of RAM. The speed of the drive(s) that contain the Paging File, therefore, affects the performance of your system.
In addition to making sure that your system Paging File is adequately sized (see Chapter 6, “Managing Memory and Disks”), you can take additional steps to maximize the efficiency of the Paging File. The first thing you should do is put the Paging File on a hard disk partition that isn’t heavily taxed by other uses. The hard disk(s) that contain the Paging File should also be fast (i.e., have low disk access times and high data transfer rates).
You may also want to consider spreading the Paging File out across multiple physical disks, leveraging Windows NT’s ability to write to multiple drives concurrently. Don’t confuse multiple disks with multiple logical partitions in this situation. Spreading a Paging File between multiple logical volumes on the same physical disk will not improve performance and may even result in slower Paging File performance. You should also run a disk defragmentation program (such as Executive Software’s Diskeeper) on your Paging File drives regularly to maintain optimal performance.
The importance of having a fast paging file cannot be underestimated. I have seen some heavily used systems on which a dedicated drive is set up strictly for the Paging File to maximize performance. Finally, remember that no matter how fast a Paging File is, it can never compete with real physical RAM. If your system makes continual use of Paging File, your best bet would be to add more RAM.
OPTIMIZING HARD DISKS
In addition to having a fast CPU and lots of memory, it is important to choose a fast disk subsystem for your Windows NT computer to obtain optimal system performance. The reason for this is simple: no matter how fast the CPU is, your system will still be slowed down if it is constantly waiting for a slow hard disk to transfer information to it. In addition to purchasing a fast controller and hard drive(s), you may also wish to consider the use of Disk Striping (a.k.a. RAID level 0), a Windows NT disk optimization feature.
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For More Information: For more information about Disk Striping/RAID 0, see “Managing Stripe Sets,” Chapter 6. |
Using Disk Striping for Maximum Speed
You can use Windows NT’s disk striping (RAID 0) feature to increase the speed of a Windows NT Workstation computer. This technology stripes data evenly across multiple hard disks, which leverages the ability of Windows NT’s I/O system to issue concurrent reads to multiple drives. Note, however, that for you to reap the benefit of disk striping, your controller and disks must support asynchronous I/O, which essentially means you must use SCSI drives. Using IDE or EIDE drives in striped configurations is not recommended because they are not capable of the device concurrency that makes this feature attractive. To fully maximize the speed of a stripe set, consider using a second SCSI controller. By doing so, you’ll create a second SCSI channel that can share the disk I/O load with the first controller. Also, Windows NT is capable of talking to both controllers simultaneously. Finally, when you choose SCSI-based controllers and hard disks, consider those that use SCSI-3, Wide SCSI-2, or Ultra/Ultra Wide SCSI technology versus SCSI/SCSI-2. These standards support higher data transfer rates and/or wider data paths (16-bit versus SCSI/SCSI’s 8-bit) that will produce much higher performance on your NT disk subsystem.
Defragmenting Your Hard Disk
You can keep your system’s hard disks running at top speed by defragmenting them regularly. Unfortunately, Windows NT 4.0 does not currently include a defragmentation utility, so you must purchase one separately. The only disk defragmentation utility for Windows NT 4.0 is Executive Software’s Diskeeper for Windows NT; however, the new disk defragmentation API included in Windows NT 4.0 should encourage other developers to produce similar products.
OPTIMIZING LAN ACCESS
In general, optimizing speed on a LAN is a complex topic. We’ll consider it, therefore, from the Windows NT Workstation point of view. First, as mentioned earlier, be sure to use a network card that takes advantage of one of the newer system buses, such as the EISA, VLB, or PCI bus. Also, use adapters that make low use of the CPU. Whenever possible, use cards with data transfer methods other than programmed I/O (PIO), which requires the CPU to carry out I/O operations for the adapter card. Instead, choose cards that support the use of shared memory, and wherever possible, those that support bus mastering.
Also, for networks with more than one type of network support installed, make sure that the Network Access Order in the Services tab of the Control Panel’s Services applet is set to access the most frequently used network first. In the Protocols tab, check that no unnecessary protocols have been installed and be sure that you are using the fastest type of protocol for your network configuration. If you’re on a small network (200 machines or fewer) that does not require protocol routing between multiple network segments, NetBEUI will probably be your fastest protocol choice.
IDENTIFYING SYSTEM BOTTLENECKS
Perhaps the best way to optimize your system is to identify and eliminate the bottlenecks that degrade system performance. You can use either the Windows NT Diagnostics Program (for basic statistics) or the Performance Monitor application, an advanced tool that lets you analyze virtually every aspect of your Windows NT system. When you use Performance Monitor, you can monitor the objects and counters shown in Table A.1 to identify various kinds of bottlenecks:
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Special Note: To be able to use disk performance monitoring in Performance Monitor, you first issue the command diskperf -y at a Windows NT command prompt and then restart the system. This turns on disk performance monitoring counters, which are turned off by default (due to a minor performance penalty the use of these counters can produce on very slow computers such as older 486 systems). |
Monitoring these key resources in Performance Monitor provides invaluable data that lets you quickly identify system bottlenecks and discover the source of problems. Once data has been gathered using one of Performance Monitor’s views (Chart, Alert, Log, or Report), it can then be examined to see a history of the activity for each monitored resource. For more information about the use of the Performance Monitor utility, refer to one or more of the following resources: the Windows NT documentation, the Performance Monitor online help file, and Optimizing Windows NT, a book that comes with the Windows NT Resource Kit available from Microsoft Press.
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