When to avoid server consolidation comes down to how many virtual machines (VMs) can be placed onto a physical machine (PM) to reduce, avoid or save costs. With life beyond consolidation, the scenario shifts to using server virtualization to provide management transparency. Server virtualization can also be used for non-consolidation scenarios to provide transparency, flexibility as well as IT resource management agility for load balancing, business continuity (BC), disaster recovery (DR) and high availability (HA).
In general, most applications and servers can be virtualized, but not all can be consolidated due to performance, Quality of Service (QoS), availability, internal politics or turf wars, vendor support of third party applications, security and compliance. Applications and servers that have performance requirements can still be virtualized, but exercise caution with consolidation. For example, there might be a single VM on a PM to enable transparent load balancing, HA, BC and DR, while other servers may be better suited for consolidation.
This was first published in April 2010