While, virtual machines and server consolidation provides impressive and immediate ROI, it does not come without its challenges. According to Gartner, virtual machine (VM) "sprawl" is the number one concern when it comes to managing VM environments.   This article looks at VM sprawl concerns and the role that effective Virtualization Lifecycle Management (VLM) plays in preventing it from occurring in IT environments.

Most virtual servers begin by viewing a virtual machine as similar to a physical one, but without the hardware cost.  At the beginning of a virtualized deployment, virtual servers view a virtual machine the same as a physical one.   It quickly becomes clear that there are a number of significant differences between the two, making it easier to experience sprawl in the virtual world than in the physical one.

The differences:

• Mobility - Physical machines rarely move but virtual machines move a great deal.  VMs also tend to change state (e.g. powered on or off) more than their physical counterparts – another aspect of mobility.
• Volume - A fully configured virtual server can be created in minutes, meaning many are easily generated.
• Identity - A physical server has a specific identity tied to its physicality that is usually attributed to the actual hardware.  A VM on the other hand is a great deal more ethereal.
• Lifecycle velocity - VMs are created for many different reasons and life spans can be different lengths.  The speed at which a VM moves through all the stages of its lifecycle can range from minutes to years, while physical servers are more predictable.

These differences create problems for traditional datacenter management tools that tend to be built for the “physical world.”  VMs are miscounted and this lack of visibility is contributed to sprawl.

Sprawl is not defined by the number of virtual machines.  The definition of sprawl, “the proliferation of virtual machines without adequate IT control,” has more to do with control than numbers.  If growth is not controlled then the organization is in danger of sprawl.