Review: Microsoft's Virtual Server 2005

In our Clear Choice Test, Virtual Server 2005 - technology Microsoft picked up with its 2003 Connectix purchase - proved itself well worth the money ($495 for a host with up to four CPUs) because it lets you run multiple instances of Windows (NT 4.0 with Service Pack 6 on up to 2003) on the same machine. And with the Virtual Server Migration Kit, it provides a way to gracefully move and consolidate older Windows NT and 2000 Server applications onto new (and ostensibly higher-capacity) hardware. The migration kit also helps resolve Windows-specific hardware issues, such as migrating a Windows 2000 server running on an ancient SCSI host bus adapter to new storage subsystems inside the host machine with very little modification.

VMware (recently acquired by EMC) has long offered server virtualization with its ESX and GSX Server wares for a variety of operating systems . Virtual Server 2005 is not as elegant as VMware's software and only officially supports Windows servers.

Virtual Server 2005 runs as a Windows service on a Windows 2003 Enterprise Server box. An administrator then can establish multiple concurrent server environments - called virtual machines - on that single physical server, each with its own limitations in terms of what resources it can access. We suggest multiple CPUs for the hardware and a great deal of RAM (a minimum of 512M bytes per virtualized server plus another 512M bytes as a base).

We easily installed Virtual Server 2005 on three hardware platforms: a dual-CPU NFrame 1600, a dual-CPU HP DL380 and a four-processor HP DL580 (see "How we did it" ).

The Virtual Server 2005 Management Console is a Web-based program, and its real estate is somewhat ugly and poorly managed. Although, the ability to monitor each of the virtualized servers via a Web page simplifies that process a great deal.

There are three ways to build a virtual machine inside a host server. The first is to install the server software onto an allocated virtual machine, which when booted appears as though it is a new server. The second method is to copy resource settings from another already-built virtual machine. These settings, along with loaded application, can be easily replicated to create additional virtual machines. The third way is to migrate a compatible server/application instance to a virtual machine using the migration kit.

After installing Virtual Server 2005, you can either use Microsoft's preset parameters or tap into the GUI to establish your own settings for each virtual machine. Those settings include disk control (size, type of disk, location and allocated space), maximum memory to be used, IP address and operation mode. Each virtual machine can be named and can use network addresses that are internal, external or on a virtual network. These virtual machines also can stand alone and not be connected to a network.

The virtual machines lock host resources - such as CD/DVD players, serial ports, parallel ports and other devices - when they use them so that other virtual machines cannot access those host resources. Other resources may or may not need to be used sequentially. As an example, disk drives can use either shared or privately allocated space but never the same files except as read-only resources. Certain resources such as external USB drives, authentication token or biometric authentication devices cannot be shared devices.