With Microsoft's Virtual Server 2005 R2, administrators can manage multiple virtual machines at a glance without having to be physically present at the host server. This article will provide a brief overview of some key features of Virtual Server 2005 R2 (VS2005R2), including how virtual servers are managed and accessed through the system and some implications of those features.
VS2005R2 administration is performed through a Web browser rather than through an application interface. Because most program use doesn't take place on the actual server, using a Web browser interface spares the user from having to install a client application on the user's system.
The browser interface is used to create machines, to start and stop them, to change their configurations (memory size, locations of virtual hard disks, etc.), and to gain access to the virtual server's console. A user can connect remotely to the server through the browser or through a standalone application called the Virtual Machine Remote Control Client (VMRCC). But accessing a remote server through the Web interface requires an ActiveX control and the VMRCC is Windows-only.
If you plan on using non-Microsoft clients to access the virtualized servers, you can get around these limitations by installing VNC or another non-platform-centric remote-control application on the virtual machine after you've finished configuring it conventionally. Making changes to the server configuration doesn't require ActiveX, but the interface seems to rely on Internet Explorer's rendering quirks to work correctly. On a side note, if you're using Firefox instead of IE on Windows, there is a plug-in available that will allow ActiveX controls to run (but beware that the controls might not behave as expected).
The Web site interface itself can be configured to a fair degree. If you click on Virtual Server | Website Properties in the left-hand column of the Virtual Server Web interface, you can control how much information is reported back about each virtual server, how often the display is automatically refreshed (which can be disabled if you find it obtrusive) and a number of other options.
Users or groups can be given varying levels of access to virtual servers, much as they can have access to files or folders constrained in certain ways. For instance, a given user or group could be allowed to access a server but not to change its properties. Note that technologies like VNC could be used to circumvent these limitations, since such a connection wouldn't be governed by these security measures.
Connections to the VS2005R2 Web site should normally be done via SSL; if you don't have SSL configured, you'll get a warning at the bottom of the page. This is especially recommended if you're accessing VS2005R2 from outside a firewall. If you're using a firewall, be sure to set SSL for basic authentication to prevent NTLM authentication problems.
When you have multiple virtual servers running on one host, you'll probably want to assign limits on the resources available to each virtual server. Click on Virtual Server | Resource Allocation and you'll see a list of all the available virtual servers, along with the maximum and minimum amount of CPU you can set for each.
Each server can also be assigned an index called a "relative weight", from 1 to 10,000 (the default is 100). The higher the weight, the more preference a given server gets in terms of resource allocations. Microsoft actually recommends configuring the weight of a server before setting any other values, so that VS2005R2 itself can decide how much of the CPU to devote to each virtual server. For instance, a tiny virtual server that's being run from an ISO image could be given a smaller weight than a full-sized server with an attached virtual drive. (Note that because memory usage is a hard-assigned value for a virtual server, it cannot be altered through this console.)
Virtual servers can have command-line scripts assigned to run when certain actions are performed (like turning a machine on or off) or when virtual disk space is low. These scripts can be anything from simple batch jobs to sophisticated VBScripts that make changes to server configurations via VS2005R2's COM interface. Note that because they can constitute a security risk, scripts need to be enabled through the VS2005R2 Web interface before they can be used.
Serdar Yegulalp wrote for Windows Magazine from 1994 through 2001, covering a wide range of technology topics. He now plies his expertise in Windows NT, Windows 2000 and Windows XP as publisher of The Windows 2000 Power Users Newsletter and writes technology columns for TechTarget.