Windows Server 2003 : Creating Virtual Machines (part 2) - Configuring Virtual Machines

Configuring Virtual Machines

Once your virtual machine has been created and the operating system has been installed, there are several changes you can make to improve the functionality of Virtual Server and a particular VM. Some changes can be accomplished while the machine is running, and some can be accomplished or changed only while the machine is completely shut down.

Configuring Running Virtual Machines

Some features of a virtual machine can be modified while the virtual machine is running. Here are your options:

• Change the devices that are captured.

• Pause the virtual machine.

• Save the state of the virtual machine.

• Turn off the virtual machine.

The final option listed, turning off the virtual machine, is a lot like pulling the power cord on the virtual machine. This is usually not what you intended to do. We’ve already talked about capturing devices, so we won’t cover that option again here. Pausing the virtual machine is just like it sounds. When you pause a virtual machine, it stops using any of the available processing power of the host machine. It’s a lot like putting a laptop into standby mode. You don’t release any of the memory being used by the virtual machine, but it doesn’t actually do anything while it’s paused, nor does it require any processor cycles.

Save state is the virtual machine equivalent of hibernate on your laptop. It saves the current state of the virtual machine to your hard drive, and then frees up the memory it was using. When you restore your virtual machine from the saved state, it returns to exactly where it was when you saved the state.

If you have Undo Disks enabled, you have some additional options. For a full list of possible options for a running virtual machine, see Table 2.

Configuring Stopped Virtual Machines

All changes to the hardware configuration of a virtual machine have to be done while the machine is completely shut down. Hardware changes can be made even if undo information exists. But hardware changes can not be made when the virtual machine is paused or in a saved state.

The configuration options that you can change while a machine is stopped include the following:

• Add or remove a hard drive

• Add or remove a CD/DVD drive

• Add or remove a floppy drive

• Add or remove a SCSI adapter

• Change a hard disk type (IDE or SCSI)

• Add or remove a network adapter

• Enable or disable scripts

• Enable or disable undo disks

We haven’t talked about the last option in the list. You can enable a “snapshot” capability with Virtual Server that allows you to make changes to a virtual machine and then simply abandon those changes and return to a known state. To enable this, you need to turn on Undo Disks for the particular virtual machine. Then, when you shut down or save the state of a virtual machine, you have the option to commit the undo disks (move the fallback position to the current state), discard the undo disks (rollback to the fallback position), or simply save the current state without changing the undo status. This is a powerful capability that lets you repeatedly test a configuration change on your test network to see whether it’s a good idea to make the change. Once you’ve tried it, you can roll back to the original condition and try it a different way.

Installing Virtual Machine Additions

A useful add-on to Virtual Server is Virtual Machine Additions. These improve the integration of the guest operating system in the host computer and the overall performance and manageability of the virtual machine. Among other things, they get rid of the trapped mouse problem. Virtual Machine Additions are available for the following versions of Windows:

• Microsoft Windows Server 2003 (all versions)

• Microsoft Windows 2000 Server

• Microsoft Windows NT Server 4.0 with Service Pack 6a (SP6a)

• Microsoft Windows XP (all versions)

• Microsoft Windows 2000 Professional

• Microsoft Windows Millennium Edition

• Microsoft Windows 98

• Microsoft Windows 95

To install Virtual Machine Additions, perform the following steps:

1.	Log on to the Virtual Server Administration Website if you aren’t already logged on.
2.	Click Master Status in the Navigation section of the leftmost frame.
3.	Highlight the virtual machine you want to install the additions to, and select Edit Configuration from the action menu.
4.	Click Install Virtual Machine Additions in the Status window.
5.	Select the Install Virtual Machine Additions box in the Virtual Machine Additions Properties page, as shown in Figure 10, and click OK. Figure 10. The Virtual Machine Additions Properties page
6.	In the virtual machine, the installation will start automatically if the virtual machine is running. When the installation completes, reboot the guest operating system.