If you frequently test hardware, operating systems, and applications, you know that you're likely to spend many frustrating hours rebooting while you troubleshoot problem apps, drivers, services, and patches. If so, creating a test lab using virtual machines software will save you a lot of downtime.
Two popular applications are Virtual PC (formerly made by Connectix, but recently purchased by Microsoft) and VMware.
Virtual PC software allows you to install and run guest operating systems within your computer's operating system, which acts as a host. The virtual systems share the workstation's devices and are stored in files. Therefore, each virtual machine is isolated from the other and from the host; if one fails, the host machine and all the other virtual machines remain unaffected. You can continue to work while you reboot a crashed guest.
In addition to testing, VMware and Virtual PC allow you to run different platforms and platform-specific software that may be incompatible with your OS. For example, within Windows 2000, you could run a Linux Web server and test Office 2003 on Windows XP. Further, workstations equipped with virtual guest systems allow you to consolidate training and IT support onto fewer workstations.
VMware and Virtual PC share similar features and concepts. The major differences between the two are that VMware versions support Linux either as a guest or host operating system, while Virtual PC does not, and that one Virtual PC version allows you to run Windows within Mac operating systems.
Installation, hardware, and software requirements
Register for a VMware licence at www.vmware.com, then download the approximately 21MB program file. If you prefer to test the software first, you can register for a free 30-day demo.
VMware Workstation 4.0 for Windows can be installed on Windows NT, 2000 (workstations and servers), Windows XP Professional and Home Edition, and Windows Server 2003. For more specific information about host requirements, see the VMware Workstation specs.
VMware 4.0 supports the following guest operating systems:
- MS-DOS 6.x
- Windows 3.1 through Windows XP workstations
- Windows Server 2003 Web, Standard, and Enterprise editions
- Red Hat Linux 7.0-9.0
- Red Hat Linux Advanced Server 2.1
- Mandrake Linux 8.2 and 9.0
- SuSe Linux 7.3 through SLES 8
- Turbolinux Server 7.0, 8.0, and Workstation 8.0
- FreeBSD 4.0-4.62 and 4.8.
- NetWare 5.1 and 6.0
The minimum hardware requirements for running VMware Workstation 4.0 are:
- 500 MHz CPU (multiprocessor systems are supported)
- 128 MB of RAM (256 suggested, but you can apportion up to 1 GB of RAM between virtual machines)
- 100 MB of free disk space
To enable VMware to run more than one guest OS at a time, you will need much more than the CPU and RAM minimums. Your test station will benefit from a processor of at least 1 GHz, 1 GB or more of RAM, and separate hard drives for each virtual machine you plan to run simultaneously so they won't compete for read/write operations.
There are several other reasons for reserving plenty of disk space for virtual machines. Each time you save a guest OS configuration (called a Snapshot, discussed below), you need enough file space to store it. Further, your virtual disk can be configured to grow dynamically. (You can choose to automatically split virtual disks into 2GB files as they grow.) At some point, you will need to defragment and shrink your virtual systems. To do so, you'll need somewhat more free space than the amount taken up by the virtual disk files.
For example, if you plan to allow a virtual Windows XP installation to grow to 10 GB, leave about 22 GB on a hard drive. If you plan on taking periodic Snapshots of the disk configuration, then leave about 30 or more GB on the drive.
Once VMware is installed, you use it to create a test lab by:
- Configuring new virtual machines
- Installing operating systems
- Adding VMware Tools to each guest OS
- Installing applications, patches, and updates
- Using Snapshots to save test configurations
- Copying, backing up, moving, and renaming virtual disks
Configuring new virtual machines
To create a new virtual machine, choose File | New | New Virtual Machine from the VMware menu. Choose Custom Installation. Pick a guest operating system from the drop-down list. Next, set a name and a location for the new virtual machine.
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