After users have worked with virtual machines (VMs) in their environments, you might want to consider adding more VMs to the laboratory. You'll also want to examine associated software licenses. If you decide that the free or evaluation technologies you used met your needs, consider buying them. The VM running System Center Virtual Machine Manager (SCVMM), for example, can be activated using the proper product key once you've acquired it. That way, you don't need to restart the deployment process. You can simply activate the machine you're already using.
You may also want to investigate using storage area networks (SANs) to centralize all files comprising your VMs in an effort to improve laboratory performance. SANs cost more money, so you won't want to move to this level until the
If you face recalcitrant testers and developers, you can actually perform the migration without telling them you have done so. Because SCVMM lets you perform online P2V conversions -- converting the system while users are working on it -- you can activate the new VM on the sly. One administrator converted all of the company's new systems to VMs without telling anyone in the organization. Later, when the CIO said it was time to convert all systems to virtualization, he was surprised to learn that more than 60% of the infrastructure was already running on a hypervisor. Converting without telling anyone is a viable option, but should be done cautiously.
While you can use free and evaluation versions of many virtualization tools, don't skimp on other components. For example, one customer used poor-quality networking cables on host servers just because it was too much work to run another cable through the floorboards. But, each time someone walked past the host servers, the cable would pop out and users would lose contact with more than a dozen VMs.
VMs and software licensing
As you start to expand your virtualization project, you'll need to be conscious of licensing issues -- especially if you're building a permanent laboratory. Licensing VMs is very similar to how you would image disks from physical computers.
- SysPrep or Template Virtual Machine: A SysPrep VM, or one that is ready to be duplicated on your network, doesn't require a license because it is a machine that's used only to seed other machines. You don't actually use the machine as is. Once you've copied the SysPrep machine and begin personalizing it, you'll need a license for it.
- Running VMs: Each machine that is individually named and running on a constant basis needs its own license.
- Copied VMs or snapshots: Each copy of a VM does not need its own license as long as it hasn't been renamed and is using the same IP address in each copy. Because it uses the same name and has the same IP, only one copy of the machine can run at any time.
- Copied and renamed VMs: Each time you copy a VM and rename it, you need to assign a license to it. A renamed machine is treated as a completely different machine; therefore, it needs a license.
If you're running Windows infrastructures, you should be using either Microsoft Developer Network (MSDN) or TechNet Plus subscriptions for your laboratories. These subscriptions give you access to 10 or more licenses of each Microsoft product, though each license needs activation. This is the best way to test new technologies or develop new software on Windows networks.
If you're running non-Windows software or operating systems, you should verify with your manufacturer to see which licensing scheme offers the best choice for testing and development support.
Danielle Ruest and Nelson Ruest are IT experts focused on continuous service
availability and infrastructure optimization. They are authors of multiple books, including Virtualization: A Beginner's Guide and Windows Server 2008, The Complete Reference for McGraw-Hill Osborne. Contact
them at firstname.lastname@example.org.
This was first published in October 2009