Comparing Microsoft Virtual Server 2005 R2 SP1 and Windows Server 2008 Hyper-V

Unless you are running Windows Server 2008 Hyper-V or dedicated Hyper-V Server 2008 computers, Virtual Server 2005 R2 SP1 remains a viable virtualization solution for a Windows-based platform, particularly in test, development, and home-office environments that do not require x64 guest virtual machine support.

In this article, you will find Virtual Server 2005 R2 SP1 compared to Hyper-V, the newest Windows virtualization technology, within the context of base architecture, features, and management interface.

Virtual Server 2005 Overview

In September 2004, Microsoft released Virtual Server 2005, its first server-based virtualization product. Virtual Server 2005 was developed based on virtual machine technology acquired in February 2003 from the privately-held software company, Connectix. This first release supported only x86 platforms, a limited range of 32-bit host and guest operating systems, a maximum of 64 virtual machines (VMs), 3.6 GB of memory for each VM, and a single processor allocation for each VM.

In November 2005, Virtual Server 2005 R2 was released with several performance enhancing features, as well as support for x64 host operating systems, iSCSI connectivity, Non-Uniform Memory Access (NUMA), Pre-Execution Environment (PXE) booting, and Virtual Server host clustering. The last major release, Virtual Server 2005 R2 Service Pack 1 (SP1), occurred in June 2007. In this release, Microsoft added support for Intel VT and AMD-V processors, providing the ability to enable hardware virtualization on an individual VM basis. Running on an x64 host, Virtual Server 2005 R2 SP1 allows support for up to 256 GB of host physical memory and a maximum of 512 VMs. Other features include Volume Shadow Copy Service (VSS) support for snapshot-based backups, a Virtual Server host cluster script, an offline Virtual Hard Disk (VHD) mount tool (VHDMount), and additional host and guest operating system support. In May 2008, an update was released (KB948515) to extend support to Windows XP SP3, Windows Vista SP1, and Windows Server 2008, both as host and guest operating systems.

Hyper-V Overview

In parallel with the development and release of Virtual Server 2005 R2 SP1, Microsoft also worked on its next generation virtualization product, Windows Server 2008 Hyper-V, which was released in June 2008. As compared to Virtual Server, Hyper-V requires an x64 Intel VT or AMD-V platform with hardware virtualization and Data Execution Prevention (DEP). Hyper-V technology is available as a role in a full installation of Windows Server 2008, or in a server core installation of Windows Server 2008. It is also available as a free web download, in a standalone edition named Microsoft Hyper-V Server 2008, which released in October 2008.

Unlike Virtual Server 2005 R2 SP1, Hyper-V VMs support both 32-bit and 64-bit guest operating systems. Hyper-V provides the allocation of up to 4 virtual processors and 64 GB of memory to a virtual machine when running on Windows Server 2008 Enterprise or Datacenter editions. With a recent update, Hyper-V also supports up to 24 logical processors on a single host and a maximum of 192 concurrent virtual machines.

VMM Architecture Comparison

The core component of server virtualization software is the Virtual Machine Monitor (VMM). The VMM orchestrates the creation and isolation of virtual machines and controls access to system resources. As shown in Figure 1, Virtual Server 2005 R2 and Hyper-V represent two different VMM architectures: hosted and hypervisor.

Figure 1: Basic architecture of hosted and hypervisor-based VMM

In a hosted architecture, also referred to as a hybrid VMM, the VMM runs as a peer to the host operating system. This is the Virtual Server 2005 R2 implementation in which the VMM is installed as a kernel-level driver that runs at the highest x86 privilege level (Ring 0, or “privileged” mode). When a virtual machine needs to execute, the host operating system kernel yields control, and the VMM is switched onto the processor to run the virtual machine guest operating system. The VMM intercepts the guest operating system instructions and translates them into host operating system instructions, a process called binary translation, and hands control back to the Windows operating system kernel when hardware resource access is required or the VMM cannot handle a specific condition. Although Virtual Server 2005 R2 SP1 supports hardware-assisted virtualization in Intel VT and AMD-V, it is still a hosted architecture because the VMM runs in conjunction with the host Windows operating system.

In contrast, Hyper-V implements a hypervisor architecture, also referred to as a Type-1 VMM, which runs directly on the hardware below all virtual machines. Intel VT and AMD-V add a new processor mode, Ring -1, for execution of the hypervisor, retaining Ring 0 for running the virtual machines. This implementation is the basis of support for unmodified guest operating systems to run in virtual machines.

Base Features Comparison

Table 1 below summarizes base features found in Virtual Server 2005 R2 SP1, the Hyper-V role based on the Windows Server 2008 edition, and for Hyper-V Server 2008.

Table 1: Virtual Server 2005 R2 SP1 and Hyper-V Base Features Comparison

Table 2 below summarizes the host and guest operating system that are officially supported by Microsoft in Virtual Server 2005 R2 SP1 and Hyper-V. However, additional guest operating systems can run within a Virtual Server or Hyper-V VM. If a VM is not running an officially supported operating system, you may only get best effort support from Microsoft Customer Support Services (CSS) if you need assistance with an issue.

Table 2: Virtual Server 2005 R2 SP1 and Hyper-V Host and Guest OS Support Comparison

Virtual Server 2005 R2 SP1 Management Interface

Virtual Server 2005 R2 provides a web-based management interface that allows configuration and management of a Virtual Server host, as well as virtual machines. This allows remote administration from any location or device using a browser that supports ActiveX controls. As shown in Figure 2, the administrative Web application (Vswebapp.exe), referred to as the Virtual Server 2005 R2 Administration Website, allows an administrator to manage only a single Virtual Server host at a time.

Figure 2: Virtual Server 2005 R2 SP1 Administration Website – Master Status Page

However, it is a simple matter to switch the management focus to a different Virtual Server host. Figure 3 shows the Specify Virtual Server form that is displayed when accessed from the Virtual Server Manager navigation menu. This form is where you can specify the name or IP address of a Virtual Server host that you would like to manage.

Figure 3: Virtual Server 2005 R2 SP1 Administration Website – Specify Virtual Server

In addition to managing all aspects of a Virtual Server host, the Virtual Server 2005 R2 Administration Website allows you to create, add, or configure virtual machines, virtual hard disks, and virtual networks on the managed Virtual Server host. All configuration tasks are accomplished by selecting the desired management option and then providing or changing information through simple forms.

Hyper-V Management Interface

In Hyper-V, the out-of-the-box, graphical management interface is a new Microsoft Management Console (MMC) named Hyper-V Manager, shown in Figure 4. Hyper-V Manager is installed when the Hyper-V role is configured in Microsoft Windows Server 2008. It is also available for Microsoft Vista with SP1 (x86 and x64) as a web download.

Figure 4: Hyper-V Manager MMC

Conclusion

Although high-level, the information in this article should help you determine if you can leverage Virtual Server 2005 R2 SP1 on computers that do not run Microsoft Windows Server 2008 with Hyper-V. Virtual Server 2005 R2 SP1 provides reasonable performance and supports recent operating system releases as guest virtual machines. It is available as a free download and runs on Windows Server 2003, Windows XP, and Windows Vista.