Many agencies have begun using more than one server hypervisor for virtual machines (VMs). The use of multiple or tiered hypervisors addresses different challenges, similar to the use of tiered physical servers and storage hardware. For example, some environments use one type of server virtualization software for premium functionality on some physical machines and another to provide different functionality to meet management, agility or cost objectives.
Tiered hypervisors can be run in different configurations. For example, an agency can run multiple server hypervisors on the same physical blade or server or on separate servers. Having different tiers or types of hypervisors for server and desktop virtualization is similar to using multiple kinds of servers or storage hardware to meet different needs. Lower-cost hypervisors may have lacked some functionality in the past, but developers frequently add powerful new capabilities, making them an excellent option.
Tip 1: Use Nesting Carefully
Generally, IT shops should run a single hypervisor per blade or rack server, but administrators sometimes run multiple hypervisors (using either the same virtualization software or different programs) on the same physical machine, a practice known as nesting. For example, a setup that uses VMware vSphere installed on a physical machine (with virtualization technology enabled) may have various guests. In addition, various operating systems and virtual storage appliances may be guests in this environment, and one or more other guests may be a different hypervisor.
IT administrators can use nesting for testing setups in which performance or availability may not be a primary concern but which require the appearance of more physical machines. IT shops that are considering nesting should pay attention to details that will affect the situation, such as which hypervisors can be nested and how much main memory is needed.
Tip 2: Use Tiering to Cut Costs
IT departments can reduce expenses by implementing tiered or multihypervisor environments. Lower-cost hypervisors can be employed for more mundane tasks, while pricier software handles mission-critical workloads. Administrators who are proficient at managing multiple hypervisors also are likely to be able to find price advantages with vendors.
Tip 3: Ask These Important Questions
IT administrators who are considering the use of tiered or multiple hypervisors should know the answers to these questions:
- How will the different hypervisors be managed?
- Will the environment need new management tools for backup, monitoring, configuration, provisioning or other routine functions?
- Do existing tools provide support for different hypervisors?
- How will IT migrate virtual machines and their guests between different hypervisors?
As IT shops employ multiple hypervisors, they must align each hypervisor technology to the use it’s best suited for. Administrators also must make sure they have sufficient dynamic RAM to meet the demands of the multiple hypervisors.
Tiered and multiple hypervisors are an important development for federal IT. Administrators must give careful consideration to how they will use different tools in different applications or scenarios.