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Virtual Machine Sprawl: What Does It Cost You?

When "true-up" time comes, you may need a nitroglycerin pill instead of having a glass of champagne.

Virtual machines: Easy to create, easy to deploy, and easy to spiral out of control; virtual machine sprawl is the new virus in IT data centers and it’s increasing your total cost of ownership. Virtual machine sprawl, also referred to as virtual sprawl, is the creation and deployment of virtual machines without proper inventory control. A technology sold as money saving often has the opposite effect when left unchecked.

How does virtual sprawl cost you money? Let’s look at the big three money-eating consequences of virtual sprawl to illustrate how it costs you money.

  • Licensing
    Enough to make even the most liberal amongst us cringe with visions of audits and large bills presented to us by the “software cops”, licensing is the largest and most frightening aspects of virtual machine sprawl. Operating systems and applications have license fees associated with them, usually on a per installation basis. You owe a license fee whether the machine is on or off. If the operating system or application exists on a virtual machine, it counts as used. All those “test” machines you create count too.

    You say you’re using Linux and all free software? Great. Good for you. See number 2.

    Rule of Thumb: Remove unused virtual machines and return their licenses to the available pool.

  • Space
    Yes, I know it’s the final frontier but it’s also a major cost for businesses. There’s never enough of it and it’s expensive — I don’t care how much you paid for your 500GB MyBook — it’s different and you know it. With a default minimum of 8GB for virtual machines, space vanishes at an alarming rate when creating virtual machines. A 250GB array doesn’t last long at a minimal 8GB per virtual machine. That’s 31 8GB virtual machines. Where do you put your backups? How many days can you keep?

    When calculating virtual machine costs, include disk real estate costs for those virtual machines, snapshots, and backups. Do you really need a 20GB virtual machine for that desktop or is 4GB adequate?

    Rule of Thumb: Create virtual machines as you need them and minimize their sizes.

  • Time
    Don’t fool yourself into thinking that managing virtual machines doesn’t take time; it does. It may take more time that you anticipate to rid yourself of the virtual sprawl demon. You believe that all existing virtual machines are in some sort of inventory but you’d be wrong since it’s easy enough to remove a virtual machine from inventory without removing the virtual machine from disk. A properly inventoried virtual environment requires time and time is money.

    The best way to keep track of virtual machines whether they are on, off, inventory-visible, or inventory-hidden is to use an automated inventory process to locate virtual machines. Use inventory scripts setup to search for disk images and VM configuration files to estimate disk usage by those images.

    Rule of Thumb: Save time by using automated virtual machine inventory “search and report” scripts.

After you’ve mitigated the existing virtual sprawl problem in your data center by following the rules of thumb above, how do you keep it from happening again?

  1. Create a License Checkout System — You’ll be able to keep track of licenses with a checkout system that allows administrators to use licenses on an as needed basis. If your inventory script shows that you have virtual machines that are unaccounted for, remove them and return their licenses to the available license pool. Keep your software licensing under control or when “true-up” (software licensing audit) time comes, you may need a nitroglycerin pill instead of having glass of champagne.
  2. Define Acceptable Disk Use Parameters for Virtual Machines — Define the acceptable sizes for virtual machine disk use. Set aside predefined limits for server systems, desktops, virtual machine swap/pagefile space, and personal storage. With predefined limits, you’ll be able to accurately calculate storage requirements and predict future needs as growth occurs.
  3. Automate Time-Consuming Tasks — Use virtual machine templates to shorten virtual machine provisioning times and automate repetitive tasks using your virtualization software’s built-in APIs or with shell scripts available on your host operating system.

Virtual sprawl represents real costs to you through wasted software licenses, storage space, and time. Don’t allow ease of virtual machine creation cost you a bundle at true-up when you can take preventative action now and enjoy that well-deserved glass of champagne.

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