Windows NT ...: Reducing Total Cost of Ownership - Chapter 9 - Performance Monitorin Page 1 of 13 [Figures are not included in this sample chapter] Windows NT Network Management: Reducing Total Cost of Ownership - 9 - Performance Monitoring AN OLD ADAGE SAYS, "IF YOU can’t measure it, you can’t manage it." Even if you can measure something, how can you tell if your changes are making a difference if you don’t have baseline information? It’s important to monitor a server’s or work- station’s performance to maximize your investment in these tools. If a user complains that her computer is too slow, you often need more information to fix the problem. For example, if the problem is loading Web pages on a computer using an analog modem, the modem is probably limiting the system’s performance. However, if the computer is an older model, certain operations may wait for the CPU to finish processing. In this case, a complete system upgrade may be the best solution. The usefulness of performance monitoring goes far beyond handling user expectations. A network and systems administrator can use information obtained by analyzing the operations of existing hardware, software, and networking devices to predict the timing of upgrades, justify the cost of replacing and upgrading devices, and assist in troubleshooting. Performance monitoring ultimately reduces TCO and is a vital part of managing any IT environment. Performance monitoring helps answer important questions about your current environment. For example, you may want to know which activity specifically uses the most resources in your environment. If you determine that it is loading Web pages, then upgrading the RAM or the CPU speed of client machines may not help much. Here the performance bottleneck is likely to be the remote access device. With modern desktop computers and analog modems, the latter is often the point of slowest data throughput. The details of performance monitoring--which tools to use and which information to track--are largely based on the specifics of your environment. For example, suppose the user complaining of a slow computer is connected to a network with Internet access. The administrator might want to check basic network utilization statistics--perhaps the new marketing database application is causing a lot of collisions on this subnet, thereby reducing overall performance. On the other hand, if this machine is a home computer using a modem to dial up an Internet service provider, the best place to check would be the modem itself. In this chapter, we look at some good ways to monitor performance levels. Windows NT includes tools that are designed to profile hardware, software, and network metrics. After reading this chapter, you should have a better idea of what’s going on in your own environment. Performance Monitoring Methodology To monitor performance, you need to have a baseline of information. This baseline should be file://I:\chapters\z\zc846.html 3/21/01 Windows NT ...: Reducing Total Cost of Ownership - Chapter 9 - Performance Monitorin Page 2 of 13 compiled over time and should be used for measuring any significant changes to your system. A nagging question that may have occurred to you is, By measuring performance, am I not actually decreasing it? And the definitive answer is, Sometimes. In some cases, performance monitoring may present a significant drain on resources. For example, the Windows NT Performance Monitor application itself uses CPU time, memory, and display resources. On modern systems, however, this drain is negligible. In this chapter, I note where significant performance reductions may occur. Whether you are running the Performance Monitor application or not, Windows NT automatically keeps track of performance data for tuning itself. Therefore, it does not matter if you measure 100 different parameters or only 1. The impact of running Performance Monitor also remains constant for most types of monitoring, so you need not worry about it as long as you consistently use the same tool to measure performance. When you’re monitoring performance, it is always a good idea to make only one change at a time. This way, you can measure the effects of modifying a single parameter. Also, if performance decreases or other problems come up, you’ll know what to change to return to the original configuration. Documenting performance values is just as important as making changes. Windows NT includes several tools that can aid in the evaluation of performance. This chapter covers three of them: l Performance Monitor l Task Manager l Network Monitor The Windows NT Performance Monitor The Windows NT Performance Monitor is installed by default with all Windows NT installations. You open Performance Monitor by clicking Start, Programs, Administrative Tools, Performance Monitor. The program starts with the default, blank Chart view, which is one of the four Performance Monitor views. We discuss these four modes and their typical uses later in this chapter. For now, you can switch between them by clicking on the View menu and then choosing one view at a time. The settings for each view are independent of the values examined in other views, so you can specify different counters for each at any time. The Performance Monitor includes many counters and objects with which you can monitor certain aspects of system performance. Counters are general aspects of the system that can be monitored (for example, memory, processor). Objects are the actual details you wish to track for the selected object (for example, bytes committed, processor utilization). To add a counter to the default view, click on the Add button and view the various options. In the Add dialog box, you can click on the Explain button for more information about each option (see Figure 9.1). Table 9.1 lists some of the most useful measurements. Some counters include instances if multiple items are available. For example, on a dual-processor server, you can choose to monitor data for one or both processors. Note that the guidelines in the Usefulness column should be taken as generalizations for sustained levels. For example, pages/sec often goes above the recommended value for short periods of time. file://I:\chapters\z\zc846.html 3/21/01 Windows NT ...: Reducing Total Cost of Ownership - Chapter 9 - Performance Monitorin Page 3 of 13 FIGURE 9.1 Adding a counter to Performance Monitor. TABLE 9.1 Useful Performance Monitor Counters and Objects Counter Object Meaning Usefulness Memory Pages/sec The number of times/ seconds the If sustained greater than five, memory subsystem had to get you may want to consider a information from the hard disk RAM upgrade. Logical % Free Space Percentage of free space per volume A value of less than 10% Disk or per all volumes indicates that additional storage space is needed. Physical Avg. Disk The number of tasks that had to wait If high, disk performance may Disk Queue Length for disk-based data not be sufficient. Server Bytes Total/sec The amount of data transferred by High values indicate many this server and/or large file transfers to and from the server. Server Server Sessions Number of active processes on this Indicates current activity; use to server compare loads on different machines. Network % Network Percentage of total network If sustained greater than 40%, it Segment Utilization bandwidth in use may be decreasing performance. Redirector Reads/writes Rejected requests for data transfer Large file transfers may be denied/sec occurring to/from this server. The objects and counters that are available are based on the services and applications installed on the local machine. For example, if you have the Remote Access Service (RAS) installed, the RAS Port and RAS Total counters are available. These counters help you determine the current status of your remote access users. Microsoft ships Windows NT with basic performance counters enabled. For most systems administrators, these defaults are sufficient. If you require more specific information, however, you can also enable other counters and objects. For example, to measure disk performance, you need to specifically turn on disk performance logging. To do so, you must go to a command prompt and type diskperf -ye (the y flag activates disk performance monitoring, and the e flag specifies performance monitoring for stripe set volumes). This change takes effect the next time you restart the system. Why isn’t this option enabled by default? Well, keeping track of disk performance information creates a slight decrease in performance (Microsoft estimates less than 5% in most cases). Whether this slowdown is worth the additional information depends on your environment and the use of the server. To monitor various network performance values, you also need to add the Simple Network Management Protocol (SNMP) service and the Network Monitor Agent in the Network Control Panel applet. Figure 9.2 shows a Performance Monitor chart while performing a large file copy over the network. This example includes the counters and objects in Table 9.2. Note that certain instances are system specific. For example, the instance for % Network Utilization is a 3Com Etherlink III network file://I:\chapters\z\zc846.html 3/21/01 Windows NT ...: Reducing Total Cost of Ownership - Chapter 9 - Performance Monitorin Page 4 of 13 interface card. Although the type of information captured is the same, the specific names of instances will be based on the network adapter or adapters present in your system. Similarly, if you are monitoring a multiprocessor system, instances will be available for viewing statistics on one or all of the processors. TABLE 9.2 Performance Monitor Values Measured During a Large File Copy Object Counter Instance Processor % Processor Time 0 LogicalDisk Free Megabytes Total Memory Pages/sec N/A Server Bytes Total/sec N/A Network Segment % Network Utilization El3c5741 FIGURE 9.2 Performance Monitor values during a large file copy over the network.