Executive Summary:
Microsoft Windows Server 2008 R2 provides numerous enhancements over Windows Server 2008, including 64-bit computing, a new Hyper-V release, Live Migration, the Active Directory Administrative Center (ADAC), remote system management with Server Manager, the rebranding of Terminal Services to Remote Desktop Services, the PowerShell Integrated Scripting Environment (ISE), support for the .NET Framework in Server Core, the inclusion of IIS 7.5, and power management through Core Parking and ACPI P-states.

Although it seems hard to believe, the next release of Microsoft's server OS, Windows Server 2008 R2, is right around the corner. At press time, Server 2008 R2 was in beta and scheduled for release late this year. Let's dive in and take a look at some of the most important new features in Server 2008 R2.

The Exclusive 64-Bit Club

Server 2008 R2 is the first Microsoft Windows Server OS to take the 64-bit–only road. This enhancement shouldn't be a problem for new installations, because most of today's servers are x64 compatible. However, Server 2008 R2 won't run on older 32-bit servers. Existing 32-bit applications can run on Server 2008 R2 by using the OS's 32-bit compatible Windows-On-Windows (WoW) subsystem.

In addition to going 64-bit–only, Server 2008 R2 also benefits from scalability enhancements. Server 2008 R2 can address as many as 256 logical processors on one server—up from a maximum of 64 in the original Windows Server 2008 release.

New Hyper-V Release

Another important enhancement in Server 2008 R2 is the inclusion of a new release of Hyper-V. A prerelease version of Hyper-V was shipped with the original Server 2008, then the final release was added as an update. The Server 2008 R2 version of Hyper-V can use more than 32 logical processors on the host virtual machine (VM). This new Hyper-V release can take advantage of the latest Intel and AMD Second Level Address Translation (SLAT) hardware virtualization support. SLAT lets the hypervisor dispense with shadow page tables and handles the translation of VM memory to physical memory, resulting in improved VM performance. Hyper-V in Server 2008 R2 also increases the memory support for VMs to 64GB. TCP offload and jumbo frames provide improved networking performance. Another enhancement to Hyper-V in Server 2008 R2 is enhanced support for PowerShell management via a set of dedicated cmdlets. However, the single most important feature in Server 2008 R2 related to virtualization is support for Live Migration.

Live Migration

Live Migration is Microsoft's answer to VMware's VMotion. Live Migration lets you move Hyper-V VMs between Server 2008 R2 hosts with no downtime. Like VMotion, Live Migration allows the administrator to handle planned downtime scenarios with no loss of VM availability. Live Migration requires Windows Failover Clustering and leverages Windows Clustering Services and the new Cluster Shared Volumes technology to move VMs between hosts in milliseconds. Server 2008 R2's new Cluster Shared Volumes technology lets multiple cluster nodes concurrently access the same LUN, which in turn lets them access the same Virtual Hard Disks (VHDs). Thus, the VHDs don't need to be physically moved to perform a Live Migration. Figure 1 shows an overview of how Live Migration works.

Figure 1: Live Migration Overview

To perform a Live Migration, the administrator initiates the migration of a VM from the source node to a target cluster node. Live Migration creates a container VM on the target node. You don't need to move the VHD, because Cluster Shared Volumes gives the target node full access to the VHD file stored on the SAN. Next, the source VM's current memory is copied to the target node. Clients connected to the source VM continue to run, and all the changed memory pages in the source VM are mirrored. The mirrored pages are then copied to the target VM until the delta is zero or until a finite number of iterations are reached. At that point Live Migration pauses the VM on the source, copies any remaining dirty pages, copies the partition state, starts the VM on the target node, and redirects all of the client connections from the source VM to the target VM. The migration is then complete and the source VM is deleted.

Active Directory Enhancements

From a Windows administrator's perspective, the biggest change in Server 2008 R2 is undoubtedly the new Active Directory Administrative Center. The ADAC provides a brand-new task-driven interface for managing Active Directory (AD). The older Users and Computers, Site and Services, and Domains and Trusts options still exist; however, the new ADAC's task-driven interface provides a better way to handle day-to-day tasks such as working with users, computers, groups, and organization units (OUs). The ADAC is installed when you run Dcpromo to make a Server 2008 R2 system a domain controller (DC). Figure 2 shows the new ADAC.

Figure 2: Active Directory Administrative Center

As you can see in Figure 2, the ADAC provides breadcrumb-style navigation much like Windows Explorer. By default, the ADAC navigation pane on the left side of the screen uses either a treeview or a simple list view. However, you can also customize the view by adding commonly used containers to the navigation pane. The new ADAC can open AD using a different set of credentials than your logon credentials. It can also manage AD objects across multiple domains. The current version of the ADAC runs only on Server 2008 R2. Future versions of Windows 7 will also be able to run the ADAC. For more information about the ADAC, see the Microsoft TechNet article "What's New in AD DS: Active Directory Administrative Center."

A closely related AD enhancement in Server 2008 R2 is the addition of 75 new AD cmdlets. The new ADAC is built using these cmdlets. When you use ADAC to perform actions, ADAC is actually building and executing PowerShell scripts in the background.

The new Server 2008 R2 Active Directory Domain Services also has several significant improvements. A new offline domain join feature lets a computer join a domain without being connected to the domain. This feature can help automate client deployment. Another useful feature in the new Active Directory Domain Services is the new AD Recycle Bin, which lets you recover deleted AD objects without performing an authoritative restore.

Remote System Management with Server Manager

One feature that administrators love in Server 2008 is Server Manager. Server Manager provides a centralized management console that is actually useful. You can use Server Manager to manage roles and features, as well as check status and drill into event logs. However, in the original Server 2008 release Server Manager is limited to working with the local system. The Server 2008 R2 release enables Server Manager to manage both local and remote Server 2008 systems. In addition, Server Manager can be installed on Windows Vista or Windows 7 network clients, letting you perform network management tasks from client workstations.

Terminal Services Is Out; Remote Desktop Services Is In

Another change in Server 2008 R2 is the rebranding of Terminal Services to Remote Desktop Services. Table 1 lists the former names of various Terminal Services components and their corresponding Remote Desktop Services names.

Table 1: Terminal Services vs. Remote Desktop Services
Windows Server 2008 Name Windows Server 2008 R2 Name
Terminal Services Remote Desktop Services
Terminal Services RemoteApp RemoteApp
Terminal Services Gateway Remote Desktop Gateway
Terminal Services Session Broker Remote Desktop Connection Broker
Terminal Services Web Access Remote Desktop Web Access
Terminal Services CAL Remote Desktop CAL
Terminal Services Easy Print Remote Desktop Easy Print

Server 2008 R2's Remote Desktop Services changes aren't just in name alone. The new RemoteApp & Desktop Connection (RAD) includes support for the Aero Glass interface, true multi-monitor support, multimedia redirection, audio recording, and support for DirectX 9, 10, and 11 redirection.

Enhanced Scripting Functionality with PowerShell 2.0

Server 2008 R2 includes the new PowerShell 2.0 release. PowerShell 2.0 is compatible with PowerShell 1.0, has improved Windows Management Instrumentation (WMI) cmdlets, and supports running scripts on remote systems, creating Script Cmdlets, and running background jobs. More than 240 new cmdlets ship with Server 2008 R2 out of the box.

Even better, Server 2008 R2 provides a new graphical PowerShell UI for developing and debugging PowerShell scripts. The new PowerShell Integrated Scripting Environment (ISE) is a multi-tabbed graphical PowerShell development platform. The PowerShell ISE features color-coded syntax, as well as debugging capabilities that let you set breakpoints and single-step through your PowerShell scripts. Figure 3 shows the new PowerShell ISE.

Figure 3: PowerShell Integrated Scripting Environment

The PowerShell ISE development environment consists of three panes: the script pane, the output pane, and the command pane. You can see the script pane in the upper third of Figure 3; this pane is for editing and debugging your PowerShell scripts. The output pane (in the middle portion of Figure 3) displays the results of any scripts that you can run in the ISE. The command pane, which you can see in the bottom part of Figure 3, is for executing your scripts and other PowerShell commands.

.NET Framework Support in Server Core

One of the biggest disappointments in the original Server 2008 release was the lack of support for the .NET Framework in Server Core. Several technologies that seemed perfect for Server Core, such as PowerShell and ASP.NET applications, couldn't run on Server Core. Server 2008 R2 adds support for the .NET Framework versions 2.0, 3.0, 3.5, and 4.0. Support for the.NET Framework allows Server Core to run both ASP.NET applications and PowerShell scripts. However, Server Core 2008 R2 still doesn't support SQL Server or Exchange.

IIS 7.5

Another new feature in Server 2008 R2 is the inclusion of IIS 7.5. The main enhancements in IIS 7.5 are improved management and deployment of web applications. IIS 7.5 has a new PowerShell Provider for IIS, along with several new IIS task-oriented PowerShell management cmdlets. The new cmdlets provide the ability to add and change configuration properties of websites, web-based applications, virtual directories, and application pools.

IIS Manager is also enhanced with a new Configuration Editor. This feature lets you access all of the IIS 7.5 configuration settings, including settings such as FastCGI that were hidden in the previous version of IIS.

For added web application security, a new Request Filtering module provides HTTP blocking capabilities that were formerly found in the separate URLScan product. IIS 7.5 also provides improved application security by running every application pool with a unique low-privilege identity. Also included are a new Best Practices Analyzer (BPA) and updated versions of Secure FTP and WebDAV.

Going Green with Core Parking and P-states

Server 2008 R2's Core Parking feature lets the OS dynamically control the number of cores used in a multi-core server. Server 2008 R2's Core Parking continually monitors the CPU utilization of multi-core server systems. Whenever processor cores are underutilized, Core Parking can put those cores into sleep mode to reduce the power required to run the system. When the workload on the remaining cores increases, the suspended cores are reactivated and full processing power returns. For example, Core Parking could enable a server with 64 logical cores to drop back to just a 2-core machine during low-utilization times, then restore the server to a full 64-core system when the workload rises. Notably, with Core Parking one core must always remain active in order to control the state of the other cores.

Another power-management feature built into Server 2008 R2 is the ability to adjust processors' Advanced Configuration and Power Interface (ACPI) P-states. This feature essentially allows very granular control over a system's power consumption. Altering the P-state of the processor governs the frequency of the CPU. Running the processor cores at lower frequencies is another way to reduce power consumption. Both Core Parking and ACPI P-state status can be controlled through new Group Policy settings.

Best Windows Server OS Yet

Server 2008 R2 adds a lot of value to the Server 2008 OS, with features such as Live Migration, the new ADAC, and the PowerShell ISE. Other important features include enhanced DNS and DHCP security, read-only DFS Replication (DFSR), and the ability to boot from VHD. Connecting Windows 7 to Server 2008 R2 provides even more benefits; for more information, see the sidebar "Windows Server 2008 R2 and Windows 7: Better Together." In addition to the big-ticket items, Server 2008 R2 provides numerous smaller changes. For an overview of these changes, see the sidebar "The Little Things About Windows Server 2008 R2."

I used the beta version to evaluate Server 2008 R2; some features will likely change before the final release. However, Server 2008 R2 is clearly the best release of the Windows Server OS yet.