Ars Technica has had a great series of articles recently on virtualization (1 2 3 4 5).
But a statement made in part 5 repeated what has been too-often stated as a benefit of virtualization: the reduction of servers, and associated management tasks –
The benefits of performing a large-scale P2V conversion are pretty clear: server consolidation leading to reduced space and power usage and decreased heat output; easier centralized management; new redundancy and high-availability options (including the ability to restore or clone entire VMs at a time); and the opportunity to rebuild the OS of legacy systems, to just name a few. It is very possible to consolidate even a dozen racks’ worth of servers into a single rack, or just two blade chassises. With gains like that, it is no wonder that virtualization is quickly becoming entrenched in the enterprise.
Virtualization does NOT guarantee reduction of servers and management tasks – it can enable the reduction of physical servers in the infrastructure, but because of the ease of spinning-up a new server for testing, development, or just “because”, virtualization has actually lead to a proliferation of servers on the network when they would not have been previously feasible.
If build time is 10 minutes for a VM (typical in environments I have seen/used), then any time someone needs/wants a new server, it can be ready in a few minutes. That’s amazing. The problem is that when it is no longer needed, it needs to be powered-down and have its assigned resources returned to the pool. Sadly, this rarely happens.
There are indeed tools that can help enable this (I was recently trained on one such tool (and, I think, it’s the single best option for the job)), but out-of-the-box, virtualization doesn’t help anything except to reduce the physical footprint of the data center.