One of the downsides of multiple processors is the management of interrupts.The first CPU in a multiprocessor system (processor 0) controls I/O. If an application running on another CPU requires a lot of I/O, CPU 0 can spend much of its time managing interrupts instead of running an application. Windows Server 2003 manages multiple processors and interrupts quite well, but there is a way to tune the affinity of a thread to a specific processor. Processor affinity is a method of associating an application with a specific CPU. Processor affinity can be used to reduce some of the overhead associated with multiple CPUs and is controlled pri- marily via the Task Manager utility. Priority is a mechanism used to prioritize some applications (or threads) over others. Priority can be set when an application is started or can be changed later using the Task Manager utility. Disk The disk is the permanent storage location of the operating system, applications, and data. A disk is made up of one or more physical drives. Often, a computer system will contain multiple disks con- figured in arrays, which can be useful for increasing performance and/or availability. Several factors contribute to the performance and reliability of disk: ■ The disk controller technology ■ The life-expectancy (MTBF) of the drive(s) ■ The way data is arranged on the drive(s) ■ The way data is accessed on the drive(s) ■ The ratio of drive controllers to the number of drives Network Components The primary (and default) communications protocol used by Windows Server 2003 is TCP/IP.The operating system also supports the next generation of the TCP/IP protocol, IP version 6 (IPv6), as well as the AppleTalk, Reliable Multicast, and NWLink protocols. Multiple protocols installed on a system consume additional memory and CPU resources. Reducing the number of protocols in use will improve performance. On systems that do have multiple protocols loaded, change the binding order of the protocols to the NIC so that the most frequently used protocol is bound first.This will reduce the amount of processing needed for each network packet and improve performance. When a packet is received by the NIC, it is placed in a memory buffer.The NIC then either generates an interrupt to have the CPU transfer the packet to the main memory of the computer or performs a direct memory access (DMA) transfer and moves the data itself.The method used depends on the hardware involved.The DMA transfer method is much faster and has less impact on the overall system. The number and/or size of the memory buffers allocated to the NIC can affect performance as well. Some NICs allow you to adjust the number of memory buffers assigned to the card. A larger buffer space allows the NIC to store more packets, reducing the number of interrupts the card must generate by allowing larger, less frequent data transfers. Conversely, reducing the number of buffers 246 Chapter 7 • Planning, Implementing, and Maintaining a High-Availability Strategy 301_BD_w2k3_07.qxd 5/11/04 5:01 PM Page 246 can increase the amount of interrupts generated by the NIC, impacting system performance. Some NICs allow you to adjust the buffers for transmitting and receiving packets independently, giving you more flexibility in your configuration.The trade-off of increasing communication buffers may be a reduction in the amount of memory available to applications in the system. One feature of Windows 2000 and Windows Server 2003 is support for IP Security (IPSec). This feature allows the securing of data transmitted over IP networks through the use of cryptog- raphy. IPSec is computer-intensive, meaning that significant amounts of CPU overhead are incurred with its use. Some NICs made in recent years support the offloading of the IPSec calculations to a highly optimized processor on the NIC.This can greatly reduce the amount of CPU time needed, as well as improve communications performance. NICs that support the offloading of IPSec are not much more expensive than regular NICs and should be strongly considered if you are using IPSec. Another consideration for network performance is the network topology. Although it is not specific to the Windows operating system, network topology can greatly affect communications per- formance. If the traffic to your server must travel through routers that convert large incoming packets into multiple smaller packets, your server must do more work to reassemble the original packets before your applications can use the data. For example, if a client system is connected to a Token Ring network (which commonly uses a packet size of 4192 bytes or larger) and your server is connected via Ethernet (with a packet size of 1514 bytes), an intermediary router will “chop” the original packet into three or more packets for transmission on the Ethernet network segment.Your server must then reassemble these packets before passing them to applications. Reducing the number of topologies and/or routers on your network can improve performance by reducing packet conver- sions and reassembly. Also, when using Ethernet, consider using switches instead of hubs. Switches are more expensive but allow higher communication rates and also permit more than one device to communicate at the same time. Hubs are cheaper but allow only one computer to be communicating at any given time. Switches are also not susceptible to Ethernet collisions, whereas hubs are at the mercy of collisions. Another topology-related configuration is the duplex setting of the NICs. Primarily an issue with Ethernet, duplex describes how data is transmitted. A full-duplex communication link allows the simultaneous transmission and reception of data. Full duplex is the desired setting for servers, because servers normally need to transmit and receive at the same time. Full duplex typically requires switches. Half-duplex communication is the bi-directional communication of data but not at the same time. When transmitting data, receiving data is not possible and vice versa. Half duplex is often acceptable for workstations but should be avoided on servers. Using the System Monitor Tool to Monitor Servers Windows Server 2003 includes tools for monitoring the performance of your server. System Monitor is one such tool. System Monitor is an ActiveX control snap-in that is available as part of the Performance administrative tool.You can start it from the Start menu, as shown in Figure 7.1. Planning, Implementing, and Maintaining a High-Availability Strategy • Chapter 7 247 301_BD_w2k3_07.qxd 5/11/04 5:01 PM Page 247 System Monitor works by collecting information from counters built in to the operating system. Counters are features of the operating system (as well as some utilities and applications) that count specific events occurring in the system (like the number of disk writes each second or the per- centage of disk space in use by files).The graphical view, shown in Figure 7.2, graphs the counter statistics. You can also see the counter statistics in System Monitor’s report view, as shown in Figure 7.3. 248 Chapter 7 • Planning, Implementing, and Maintaining a High-Availability Strategy Figure 7.1 Starting the Performance Administrative Tool Figure 7.2 System Monitor, Graphical View with Default Counters 301_BD_w2k3_07.qxd 5/11/04 5:01 PM Page 248 You can access the data collected by counters via System Monitor, other utilities, or third-party applications.This data provides you with an understanding of what is occurring on your system at the moment or over time. Using this information, you can tune your system’s operation to best suit your needs, determine if components are being overutilized, plan for expanding or replacing your system, or perform troubleshooting. Some of the most frequently used counters are shown in Table 7.1. Table 7.1 Commonly Referenced Performance Counters Performance Object: Recommended Resource Counter Threshold Comments Disk Logical Disk:%Free Space 15% Percentage of unused disk space. This value may be reduced on larger disks, depending on your preferences. Physical Disk:%Disk Time 90% If you’re using a hard- ware controller, try increasing the controller cache size to improve read/write performance. The Physical Disk counter is not always available or may be unreliable on clustered disks. Logical Disk:%Disk Time Planning, Implementing, and Maintaining a High-Availability Strategy • Chapter 7 249 Figure 7.3 System Monitor, Report View with Default Counters Continued 301_BD_w2k3_07.qxd 5/11/04 5:01 PM Page 249 Table 7.1 Commonly Referenced Performance Counters Performance Object: Recommended Resource Counter Threshold Comments Physical Disk:Disk Varies by disk The rate of read or write Reads/sec technology operations per second. Ultra SCSI should handle 50 to 70. I/O type (random/sequential) and RAID structure will affect this greatly. Physical Disk:Disk Writes/sec Physical Disk:Avg. Disk Total # of spindles The number of disk Queue Length plus 2 requests waiting to occur. It is used to deter- mine if your disk system can keep up with I/O requests. Memory Memory:Available Bytes Varies The amount of free physical RAM available for allocation to a pro- cess or the system. Memory:Pages/sec Varies Number of pages read from or written to disk per second. Includes cache requests and swapped executable code requests. Paging File Paging File:%Usage Greater than 70% The percentage of the page file currently in use. This counter and the two Memory coun- ters are linked. Low Available Bytes and high Pages/sec indicate a need for more physical memory. Processor Processor:%Processor 85% Indicates what per- Time centage of time the processor was not idle. If high, determine if a single process is con- suming the CPU. Consider upgrading the CPU speed or adding processors. 250 Chapter 7 • Planning, Implementing, and Maintaining a High-Availability Strategy Continued 301_BD_w2k3_07.qxd 5/11/04 5:01 PM Page 250 Table 7.1 Commonly Referenced Performance Counters Performance Object: Recommended Resource Counter Threshold Comments Processor:Interrupts/sec Start at 1000 on s Indicates the number of ingle CPU; 5000 hardware interrupts gen- multiple CPUs erated by the compo- nents of the system (net- work cards, disk controllers, and so on) per second. A sudden increase can indicate conflicts in hardware. Multiprocessor systems normally experience higher interrupt rates. Server Work Server Work Queues: 4 Indicates the number of Queues Queue Length requests waiting for ser- vice by the processor. A number higher than the threshold may indicate a processor bottleneck. Observe this value over time. System System:Processor Less than 10 per The number of process Queue Length processor threads awaiting execu- tion. This counter is mainly relevant on multi- processor systems. A high value may indicate a processor bottleneck. Observe this value over time. Before you attempt to troubleshoot performance issues, you should to create a baseline. Develop a baseline by collecting data on your system in its initial state and at regular intervals over time. Save this collected data and store it in a database.You can then compare this historical data to current performance statistics to determine if your system’s behavior is changing slowly over time. Momentary spikes on the charts are normal, and you should not be overly concerned about them. Sustained highs can also be normal, depending on the activity occurring in a system, or they can signal a problem. Proper baselining will allow you to know when a sustained high is detrimental. The Heisenberg Principal of physics (greatly paraphrased) states that you cannot observe the activity of something without altering its behavior.The same is true with performance monitoring. The collection of statistics requires computer resources. Collect only the counters you specifically need. If the system you wish to examine is extremely busy, consider using the noninteractive Performance Logs and Alerts function, shown in Figure 7.4, rather than System Monitor. Collecting the counters will still incur overhead, but not as much. Planning, Implementing, and Maintaining a High-Availability Strategy • Chapter 7 251 301_BD_w2k3_07.qxd 5/11/04 5:01 PM Page 251 You might also consider lowering the update interval or collecting data from the system on an hourly or daily basis, rather than continuously. If you’re monitoring disk counters, store the logs on a different disk (and, if possible, on a different controller channel) than the one you are monitoring. This will help avoid skewing the data.You can also save the collected statistics into a file or database, and then load and review them later (configured on the Source tab of the System Monitors Properties dialog box, shown later in Figure 7.11). A counter log called System Overview, shown in Figure 7.5, is provided by Microsoft as an example.This log is configured to collect the same default counters as System Monitor at 15-second intervals. You can view the properties of the System Overview log by right-clicking it and selecting Properties from the context menu. Figure 7.6 shows the dialog box that appears. 252 Chapter 7 • Planning, Implementing, and Maintaining a High-Availability Strategy Figure 7.4 Performance Logs and Alerts, Accessed from Computer Management Figure 7.5 The Sample System Overview Counter Log 301_BD_w2k3_07.qxd 5/11/04 5:01 PM Page 252 The Log Files tab, shown in Figure 7.7, specifies the type (format) of the log file, its location, and the comment assigned to the log.The drop-down menu for the Log File Type option (shown in Figure 7.7) lists the formats available for log files.The binary format is compact and efficient.The text formats require more space to store the log, but they can be read by other applications like Microsoft Word and Excel.The binary circular file format overwrites itself when it reaches its max- imum size, potentially saving disk space. If you click Configure… in the Log Files tab of the System Overview Properties dialog box, you will be presented with the Configure Log Files dialog box, as shown in Figure 7.8. Here, you can specify the location, name, and size limit of the log file. Planning, Implementing, and Maintaining a High-Availability Strategy • Chapter 7 253 Figure 7.6 Properties of the System Overview Sample Log Figure 7.7 Properties of the System Overview Sample Log, Log Files Tab 301_BD_w2k3_07.qxd 5/11/04 5:01 PM Page 253 The Schedule tab, shown in Figure 7.9, lets you specify the schedule for collecting data from the selected counters.The log can be manually controlled or can be scheduled to start at a specific date and time.You can stop the log manually or after a specific duration, a certain date and time, or when the log reaches its maximum size. By default, System Monitor tracks real-time data, but you can also have it display data from log files.To view log file data, click the View Log Data button in the main System Monitor window, as shown in Figure 7.10 (the icon that looks like a disk, the fourth from the left; circled for clarity in the figure). On the Source tab, select the Log files option button and click Add. Browse to the log file you wish to view, select it, and click Open. With a log file added, the Source tab should look sim- ilar to Figure 7.11. Click OK, and you will be viewing the data collected in the log file. Figure 7.12 shows an example of viewing log file data. 254 Chapter 7 • Planning, Implementing, and Maintaining a High-Availability Strategy Figure 7.8 Configuring Log Files Figure 7.9 Properties of the System Overview Sample Log, Schedule Tab 301_BD_w2k3_07.qxd 5/11/04 5:01 PM Page 254 Planning, Implementing, and Maintaining a High-Availability Strategy • Chapter 7 255 Figure 7.10 Selecting the View Log Data Button Figure 7.11 System Monitor Properties, Source Tab Figure 7.12 System Monitor, Viewing Log File Data 301_BD_w2k3_07.qxd 5/11/04 5:01 PM Page 255 . accessed on the drive(s) ■ The ratio of drive controllers to the number of drives Network Components The primary (and default) communications protocol used by Windows Server 2003 is TCP/IP .The operating. have the CPU transfer the packet to the main memory of the computer or performs a direct memory access (DMA) transfer and moves the data itself .The method used depends on the hardware involved .The. workstations but should be avoided on servers. Using the System Monitor Tool to Monitor Servers Windows Server 2003 includes tools for monitoring the performance of your server. System Monitor is one