Windows Server 2008 R2 : Optimizing Performance by Server Roles

Microsoft also makes several other tools available that will analyze systems and recommend changes. 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.

Domain Controllers

A Windows Server 2008 R2 domain controller (DC) houses Active Directory Domain Services (AD DS) and may have additional roles such as being responsible for one or more Flexible Single Master Operations (FSMO) roles (schema master, domain naming master, relative ID master, PDC emulator, and/or infrastructure master) or a global catalog (GC) server. Also, depending on the size and design of the system, a DC might serve many other functional roles such as DNS and WINS. In this section, AD, replication, and DNS monitoring will be explored.

Monitoring Active Directory and Active Directory Replication

Active Directory Domain Services (AD DS) is the heart of Windows Server 2008 R2 domains and has been the directory of choice for years. Active Directory has continuously been improved with each release, including performance enhancements. AD DS is used for many different facets, including, but not limited to, authentication, authorization, encryption, and Group Policies. Because AD plays a vital role in a Windows Server 2008 R2 network environment and organizations rely on it heavily for communication and user management, it must perform its responsibilities as efficiently as possible.

The Directory Services Performance Monitor object provides various AD performance indicators and statistics that are useful for determining AD’s workload capacity. Many of these counters can be used to determine current workloads and how these workloads can affect other system resources. There are relatively few counters in this object, so it’s recommended that you monitor each one in addition to the common set of bottleneck objects. With this combination of counters, you can determine whether the system is overloaded and Active Directory performance is impacted.

Measuring AD DS replication performance is a complex process because of the many variables associated with replication. They include, but aren’t limited to, the following:

• Intrasite versus intersite replication

• The compression being used (if any)

• Available bandwidth

• Inbound versus outbound replication traffic

Fortunately, there are performance counters for every possible AD replication scenario. These counters are located within the Directory Services object and are prefixed by the primary process that is responsible for AD DS replication—the Directory Replication Agent (DRA). Therefore, to monitor AD replication, you need to choose those counters beginning with DRA.

Like most other server products, AD DS uses a database and its performance should also be monitored to provide an accurate reflection of AD DS performance. Understanding a domain controller’s overall system resource usage and the performance of AD DS will help you align future upgrades and changes with capacity and performance needs. As companies continue to grow, it is essential that the systems be able to grow with them, especially in regard to something critical like AD DS. Although many counters exist, some of the relevant counters necessary to monitor AD DS and the database are in Table 1. This is only a sample list and additional counters might need to be added, depending on the desired outcome of the monitoring and specific AD DS functionality.

Monitoring DNS

The domain name system (DNS) has been the primary name resolution mechanism in almost all networks and this continues with Windows Server 2008 R2. For more information on DNS. Numerous counters are available for monitoring various aspects of DNS in Windows Server 2008 R2. The most important categories in terms of capacity analysis are name resolution response times and workloads, as well as replication performance.

The counters listed in Table 2 are used to compute name query traffic and the workload that the DNS server is servicing. These counters should be monitored along with the common set of bottlenecks to determine the system’s health under various workload conditions. If users are noticing slower responses, you can compare the query workload usage growth with your performance information from memory, processor, disk subsystem, and network subsystem counters.

Comparing results with other DNS servers in the environment can also help you to determine whether you should relinquish some of the name query responsibility to other DNS servers that are less busy.

Replication performance is another important aspect of DNS. Windows Server 2008 R2 supports legacy DNS replication, also known as zone transfers, which populate information from the primary DNS to any secondary servers. There are two types of legacy DNS replication: incremental (propagating only changes to save bandwidth) and full (the entire zone file is replicated to secondary servers).

Asynchronous full zone transfers (AXFR) occur on the initial transfer and then the incremental zone transfers (IXFR) are performed thereafter. The performance counters for both AXFR and IXFR (see Table 3) measure both the requests and successful transfers. It is important to note that if your network environment integrates DNS with non-Windows systems, it is recommended that those systems support IXFR.

Remote Desktop Services Server

Remote Desktop Services Server has its own performance objects for the Performance Monitor called the Remote Desktop Services Session and Remote Desktop Services objects. It provides resource statistics such as errors, cache activity, network traffic from Remote Desktop Server, and other session-specific activity. Many of these counters are similar to those found in the Process object. Some examples include % Privileged Time, % Processor Time, % User Time, Working Set, Working Set Peak, and so on.

Three important areas to always monitor for Terminal Server capacity analysis are the memory, processor, and application processes for each session. Application processes are by far the hardest to monitor and control because of the extreme variances in programmatic behavior. For example, all applications might be 32-bit, but some might not be certified to run on Windows Server 2008 R2. You might also have in-house applications running on Remote Desktop Services that might be poorly designed or too resource intensive for the workloads they are performing.

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 environment 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 Server 2008 R2 host. These counters are shown in Figure 1.

Figure 1. Performance Monitor counters for virtualization.

The performance counters related to virtualization include the following:

• Allocated MB— Displays the amount of physical memory (RAM) allocated to each virtual server

• Allocated Pages— Displays the amount 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.