Single and multiple hypervisors

Listed are some of the benefits and trade-offs between using single and multiple hypervisors:

• Simplified management – a single hypervisor environment can be managed with a single tool, giving a global view of the entire environment. A multi-hypervisor environment may require multiple tools to manage the environment, providing a more limited view, as well as requiring administrators to understand multiple systems, configurations, etc.
• Flexibility in allocating resources – a single hypervisor environment allows administrators to reallocate resources anywhere within the environment. For example, unused or underused servers can be moved to a cluster that is approaching capacity or is experiencing performance issues. If there are multiple hypervisors, the underlying hardware may not be compatible, and minimally, the hypervisor would need to be reinstalled or changed to match the target destination. This also impacts longer-term capacity planning, as multiple environments must be analyzed independently, and runs the risk of having idle systems.

• BC and DR planning – Each hypervisor platform must be treated independently from a recovery perspective, since not all hypervisors have the same options available. This can also complicate the storage and network recovery options, as there may need to be multiple options available within those layers as well.
• Performance and compatibility – a single hypervisor may not be able to run all of the required operating systems within the data center. In addition, optimal performance might only be possible for a particular application if it is paired with a specific hypervisor. Depending on the criticality of the application and the performance improvement, this alone may be a valid reason to deploy a second hypervisor. Also, if the eventual plan is to move to a hybrid or cloud environment, ensure that the hypervisors are compatible with the provider’s systems.
• Cost – A single hypervisor will generally cost less in terms of Operational expenses. However, capital expenses may or may not be higher, depending upon factors such as licensing, hardware costs, etc.