SQL Server 2008 Hyber V Unleashed - p 27 potx

ptg6432687 240 7 Optimizing the Hyper-V Host Server and Guest Sessions TABLE 7.3 Important Counters and Descriptions Related to Memory Behavior Object Counter Description Memory Committed Bytes Monitors how much memory (in bytes) has been allocated by the processes. As this number increases above available RAM, so does the size of the pagefile as paging has increased. Memory Pages/sec Displays the amount of pages that are read from or written to the disk. Memory Pages Output/sec Displays virtual memor y pages written to the pagefile per second. Monitor this counter to identify paging as a bottleneck. Memory Page Faults/sec Reports both soft and hard faults. Process Working Set, _Total Displays the amount of virtual memor y that is actually in use. Paging file %pagefile in use Reports the percentage of the paging file that is actually in use. This counter is used to determine whether the Windows pagefile is a potential bottleneck. If this counter remains above 50% or 75% consistently, consider increasing the pagefile size or moving the pagefile to a different disk. outlines the counters necessary to monitor memory and pagefile usage, along with a description of each. By default, the Memory section of the Resource Overview in the Reliability and Performance Monitor, shown in Figure 7.17, provides a good high-level view of current memory activity. For more advanced monitoring of memory and pagefile activity, use the Performance Monitor component of the Reliability and Performance Monitor. Systems experience page faults when a process requires code or data that it can’t find in its working set. A working set is the amount of memory that is committed to a particular process. When this happens, the process has to retrieve the code or data in another part of physical memory (referred to as a soft fault) or, in the worst case, has to retrieve it from the disk subsystem (a hard fault). Systems today can handle a large number of soft faults without significant performance hits. However, because hard faults require disk subsystem access, they can cause the process to wait significantly, which can drag performance to a crawl. The difference between memory and disk subsystem access speeds is exponential even with the fastest hard drives available. The Memory section of the Resource Overview in the Reliability and Performance Monitor includes columns that display working sets and hard faults by default. Download at www.wowebook.com ptg6432687 241 Monitoring System Performance 7 FIGURE 7.17 Memory section of the Resource Over view. The Page Faults/sec counter reports both soft and hard faults. It’s not uncommon to see this counter displaying rather large numbers. Depending on the workload placed on the system, this counter can display several hundred faults per second. When it gets beyond several hundred page faults per second for long durations, begin checking other memory counters to identify whether a bottleneck exists. Probably the most important memory counter is Pages/sec. It reveals the number of pages read from or written to disk and is, therefore, a direct representation of the number of hard page faults the system is experiencing. Microsoft recommends upgrading the amount of memory in systems that are seeing Pages/sec values consistently averaging more than five pages per second. In actuality, you’ll begin noticing slower performance when this value is consistently higher than 20. So, it’s important to carefully watch this counter as it nudges higher than 10 pages per second. NOTE The Pages/sec counter is also particularly useful in determining whether a system is thrashing. Thrashing is a term used to describe systems experiencing more than 100 pages per second. Thrashing should never be allowed to occur on Windows 2008 sys- tems because the reliance on the disk subsystem to resolve memory faults greatly affects how efficiently the system can sustain workloads. Download at www.wowebook.com ptg6432687 242 7 Optimizing the Hyper-V Host Server and Guest Sessions FIGURE 7.18 Virtual Memor y configuration options. System memory (RAM) is limited in size, and Windows supplements the use of RAM with virtual memory, which is not as limited. Windows will begin paging to disk when all RAM is being consumed, which, in turn, frees RAM for new applications and processes. Virtual memory resides in the pagefile.sys file, which is usually located in the root of the system drive. Each disk can contain a pagefile. The location and size of the pagefile is configured under the Virtual Memory section, shown in Figure 7.18. To access the Performance Options window, complete the following steps: 1. Click Start. 2. Right-click Computer and select Properties. 3. Click the Advanced Settings link on the left. 4. When the System Properties window opens, click the Settings button under the Performance section. 5. Select the Advanced tab. 6. Click Change under Virtual Memory. TIP Windows will normally automatically handle and increase the size of pagefile.sys as needed. In some cases, however, you might want to increase performance and manage virtual memor y settings yourself. Keeping the default pagefile on the system drive and adding a second pagefile to another hard disk can significantly improve performance. Download at www.wowebook.com ptg6432687 243 Monitoring System Performance 7 Spanning virtual memor y across multiple disks or just placing the pagefile.sys on anoth- er, less-used disk, will also allow Windows to run faster. Just ensure that the other disk isn’t slower than the disk pagefile.sys is currently on. The more physical memory a sys- tem has, the more virtual memor y will be allocated. Analyzing Processor Usage Most often, the processor resource is the first one analyzed when a noticeable decrease occurs in system performance. For capacity-analysis purposes, you should monitor two counters: % Processor Time and Interrupts/sec. The % Processor Time counter indicates the percentage of overall processor utilization. If more than one processor resides on the system, an instance for each one is included along with a total (combined) value counter. If this counter averages a usage rate of 50% or greater for long durations, first consult other system counters to identify any processes that might be improperly using the processors or consider upgrading the processor or processors. Generally speaking, consistent utilization in the 50% range doesn’t necessarily adversely affect how the system handles given workloads. When the average processor utilization spills over the 65% or higher range, performance might become intolerable. If you have multiple processors installed in the system, use the % Total Processor Time counter to determine the average usage of all processors. The Interrupts/sec counter is also a good guide of processor health. It indicates the number of device interrupts that the processor (either hardware or software driven) is handling per second. Like the Page Faults/sec counter mentioned in the section “Monitoring System Memory and Pagefile Usage,” this counter might display very high numbers (in the thousands) without significantly impacting how the system handles workloads. Conditions that could indicate a processor bottleneck include the following: . Average of % Processor Time is consistently more than 60% to 70%. In addition, spikes that occur frequently at 90% or greater could also indicate a bottleneck even if the average drops below the 60% to 70% mark. . Maximum of % Processor Time is consistently more than 90%. . Average of the System Performance Counter; Context Switches/second is consistently over 20,000. . The System Performance counter Processor Queue Length is consistently greater than 2. By default, the CPU section of the Resource Overview in the Reliability and Performance Monitor, shown in Figure 7.19, provides a good high-level view of current processor activ- ity. For more advanced monitoring of processors, use the Performance Monitor compo- nent with the counters discussed previously. Download at www.wowebook.com ptg6432687 244 7 Optimizing the Hyper-V Host Server and Guest Sessions FIGURE 7.19 CPU section of the Resource Over view. Evaluating the Disk Subsystem Hard disk drives and hard disk controllers are the two main components of the disk subsystem. The two objects that gauge hard disk performance are the physical disk and the logical disk. Although the disk subsystem components are becoming more and more powerful, they are often a common bottleneck because their speeds are exponentially slower than other resources. The effects, however, can be minimal and maybe even unno- ticeable, depending on the system configuration. To support the Resource Overview’s Disk section, the physical and logical disk counters are enabled by default in Windows 2008. The Disk section of the Resource Overview in the Reliability and Performance Monitor, shown in Figure 7.20, provides a good high-level view of current physical and logical disk activity (combined). For more advanced monitor- ing of disk activity, use the Performance Monitor component with the desired counters found in the Physical Disk and Logical Disk sections. Monitoring with the physical and logical disk objects does come with a small price. Each object requires a little resource overhead when you use them for monitoring. As a result, you might want to keep them disabled unless you are going to use them for monitoring purposes. Download at www.wowebook.com ptg6432687 245 Monitoring System Performance 7 FIGURE 7.20 Disk section of the Resource Over view. So, what specific disk subsystem counters should be monitored? The most informative counters for the disk subsystem are % Disk Time and Avg. Disk Queue Length. The % Disk Time counter monitors the time that the selected physical or logical drive spends servicing read and write requests. The Avg. Disk Queue Length monitors the number of requests not yet serviced on the physical or logical drive. The Avg. Disk Queue length value is an inter- val average; it is a mathematical representation of the number of delays the drive is expe- riencing. If the delay is frequently greater than 2, the disks are not equipped to service the workload, and delays in performance might occur. Monitoring the Network Subsystem The network subsystem is by far one of the most difficult subsystems to monitor because of the many different variables. The number of protocols used in the network, NICs, network-based applications, topologies, subnetting, and more play vital roles in the network, but they also add to its complexity when you’re trying to determine bottlenecks. Each network environment has different variables; therefore, the counters that you’ll want to monitor will vary. The information that you’ll want to gain from monitoring the network pertains to network activity and throughput. You can find this information with the Performance Monitor alone, but it will be difficult at best. Instead, it’s important to use other tools, Download at www.wowebook.com ptg6432687 246 7 Optimizing the Hyper-V Host Server and Guest Sessions TABLE 7.4 Network-Based Service Counters Used to Monitor Network Traffic Object Counter Description Network Interface Current Bandwidth Displays used bandwidth for the selected network adapter Server Bytes Total/sec Monitors the network traffic generated by the Server service such as Network Monitor, discussed earlier in this chapter in the section “Network Monitor,” in conjunction with the Reliability and Performance Monitor to get the best representation of network performance as possible. You might also consider using third- party network analysis tools such as network sniffers to ease monitoring and analysis efforts. Using these tools simultaneously can broaden the scope of monitoring and more accurately depict what is happening on the wire. Because the TCP/IP suite is the underlying set of protocols for a Windows 2008 network subsystem, this discussion of capacity analysis focuses on this protocol. NOTE Windows 2008 and Windows Vista deliver enhancement to the existing quality of ser- vice (QoS) network traffic–shaping solution that is available for XP and Windows Server 2003. QoS uses Group Policy to shape and give priority to network traffic without recoding applications or making major changes to the network. Network traffic can be “shaped” based on the application sending the data, TCP or UDP addresses (source or destination), TCP or UDP protocols, and the ports used by TCP or UDP or any combina- tion thereof. You can find more information about QoS at Microsoft TechNet: http:/ /technet.microsoft.com/en-us/network/bb530836.aspx. Several different network performance objects relate to TCP/IP, including ICMP, IPv4, IPv6, Network Interface, TCPv4, UDPv6, and more. Other counters such as FTP Server and WINS Server are added after these services are installed. Because entire books are dedicated to optimizing TCP/IP, this section focuses on a few important counters that you should monitor for capacity-analysis purposes. First, examining error counters, such as Network Interface: Packets Received Errors or Packets Outbound Errors, is extremely useful in determining whether traffic is easily travers- ing the network. The greater the number of errors indicates that packets must be present, causing more network traffic. If a high number of errors are persistent on the network, throughput will suffer. This can be caused by a bad NIC, unreliable links, and so on. If network throughput appears to be slowing because of excessive traffic, keep a close watch on the traffic being generated from network-based services such as the ones described in Table 7.4. Figure 7.21 shows these items being recorded in Performance Monitor. Download at www.wowebook.com ptg6432687 247 Optimizing Performance by Server Roles 7 FIGURE 7.21 Network-based counters in Performance Monitor. Redirector Bytes Total/sec Processes data bytes received for statistical calculations NBT Connection Bytes Total/sec Monitors the network traffic generated by NetBIOS over TCP connections Optimizing Performance by Server Roles In addition to monitoring the common bottlenecks (memory, processor, disk subsystem, and network subsystem), be aware that functional roles of the server influence what other counters you should monitor. The following sections outline some of the most common roles for Windows 2008 that require the use of additional performance counters for analyzing system behavior, establishing baselines, and ensuring system availability and scalability. Microsoft also makes several other tools available that will analyze systems and recom- mend changes. For example, the Microsoft Baseline Configuration Analyzer (MBCA) iden- tifies configuration issues, overtaxed hardware, and other items that would have a direct impact on system performance and makes recommendations to rectify those issues. Ensuring a system is properly configured to deliver services for the role it supports is essential before performance monitoring and capacity planning can be taken seriously. Download at www.wowebook.com ptg6432687 248 7 Optimizing the Hyper-V Host Server and Guest Sessions FIGURE 7.22 Performance Monitor counters for virtualization. Virtual Servers Deployment of virtual servers and consolidation of hardware is becoming more and more prevalent in the business world. When multiple servers are running in a virtual environ- ment on a single physical hardware platform, performance monitoring and tuning becomes essential to maximize the density of the virtual systems. If three or four virtual servers are running on a system and the memory and processors aren’t allocated to the virtual guest session that could use the resources, virtual host resources aren’t being utilized efficiently. In addition to monitoring the common items of memory, disk, network, and CPU, two performance counters related to virtual sessions are added when virtualization is running on the Windows 2008 host. Figure 7.22 shows these counters. The performance counters related to virtualization are as follows: . Allocated MB—Displays the amount of physical memory (RAM) allocated to each virtual server. . Allocated Pages—Displays the number of memory pages per virtual machine. The virtual session object and its counters are available only when a virtual machine is running. Counters can be applied to all running virtual sessions or to a specific virtual session. Download at www.wowebook.com ptg6432687 249 Best Practices 7 Summary Capacity planning and performance analysis are critical tasks in ensuring that systems are running efficiently and effectively in the network environment. Too much capacity being allocated to systems indicates resources are being wasted and not used efficiently, which in the long run can cause an organization to overspend in their IT budgets and not get the value out of IT spending. Too little capacity in system operations, and performance suffers in serving users and creates a hardship on servers that can ultimately cause system failure. By properly analyzing the operational functions of a network, a network administrator can consolidate servers or virtualize servers to gain more density in system resources. This consolidation may result in additional physical servers that can ultimately be used for other purposes to provide high availability of IT resources, such as for disaster recovery, as failover servers, or as cluster servers. Although it’s easy to get caught up in daily administration and firefighting, it’s important to step back and begin capacity-analysis and performance-optimization processes and procedures. These processes and procedures can minimize the environment’s complexity, help IT personnel gain control over the environment, assist in anticipating future resource requirements, and ultimately, reduce costs and keep users of the network happy. Best Practices The following are best practices from this chapter: . Spend time performing capacity analysis to save time troubleshooting and firefighting. . Use capacity-analysis processes to help weed out the unknowns. . Establish systemwide policies and procedures to begin to proactively manage your system. . After establishing systemwide policies and procedures, start characterizing system workloads. . Use performance metrics and other variables such as workload characterization, vendor requirements or recommendations, industry-recognized benchmarks, and the data that you collect to establish a baseline. . Use the benchmark results only as a guideline or starting point. . Use the Task Manager or the Resource Overview in the Reliability and Performance Monitor to quickly view performance. . Use the Reliability and Performance Monitor to capture performance data on a regular basis. . Consider using System Center Operations Manager or Microsoft and third-party prod- ucts to assist with performance monitoring, capacity and data analysis, and reporting. . Carefully choose what to monitor so that the information doesn’t become unwieldy. Download at www.wowebook.com . /technet.microsoft.com/en-us/network/bb530836.aspx. Several different network performance objects relate to TCP/IP, including ICMP, IPv4, IPv6, Network Interface, TCPv4, UDPv6, and more. Other counters such as FTP Server. www.wowebook.com ptg6432687 248 7 Optimizing the Hyper -V Host Server and Guest Sessions FIGURE 7.22 Performance Monitor counters for virtualization. Virtual Servers Deployment of virtual servers and consolidation. additional physical servers that can ultimately be used for other purposes to provide high availability of IT resources, such as for disaster recovery, as failover servers, or as cluster servers. Although