Less and less IT organizations are asking whether they should virtualize systems, and instead are focusing on how they should leverage virtualization in their environment. The maturation of virtualization solutions in the x86 and UNIX realm has opened the door to an endless array of choices. More choices offer organizations greater flexibility, but they can also introduce confusion and complexity. Every virtualization technology operates in a slightly different manner. This is compounded by the fact that every IT environment is vastly different, with its own unique operating patterns, technical compositions, and business constraints. Because of this, there’s probably never going to be one ideal virtualization technology for every IT scenario. Thus, it’s better to focus resources on choosing the right technology for a specific situation instead of finding the ever-elusive “perfect” solution.

There are several factors that influence the choice of virtualization software.

Mobility and Motioning

Motioning enables applications to move between physical servers without disruption. Available on VMware’s VMotion, XenMotion, and IBM P6 LPARs, motioning has the potential to transform capacity management. However, it’s not without its problems. Motioning can introduce volatility, and create vexing challenges for management groups tasked with incident management and compliance issues. To gauge whether motioning is a good option in the environment, organizations first need to analyze maintenance windows, consistency of workload patterns, and disaster recovery strategies.

Maintenance windows
When combined on a single physical platform, maintenance windows become intermingled. This can easy create scenarios where there is no window of time available for hardware maintenance. The same problem arises for software freezes. The ability to motion virtual machines can alleviate this problem by allowing servers to be moved offline for scheduled maintenance or software updates. Alternatively, without motioning in place, the proper initial placement of applications on virtual hosts is extremely important. In either case, making the right placement decisions is critical, since the mere act of motioning may constitute a change that violates a software freeze.