Benefits of virtualization
The Standalone Sysadmin has a nice post about where to start in the topic of virtualization.
It links to a post summarizing the benefits of this technology:
- Virtualization can reduce cost.
- Virtualization can reduce risk.
- Virtualization gives flexibility.
- Virtualization encourages aligned architectures.
I think the great power of virtualization is its flexibility, as in you do not depend on the hardware any more. Implication: if you depend on certain hardware you cannot virtualize (most of the time).
Today you have to keep hardware on stock if something fails (most of the time disks, fans, moving parts) to prevent downtime. If a virtual host fails, you just move all of your virtual guests to another host and replace it.
That shows that your infrastructure needs to be "in shape" for virtualization. You need a reliable central storage repository for the virtual machines to be able to move them easily between hosts. If you have only local storage on the hosts, moving virtual machines is only possible if the source is still available.