This article is aimed at the person investigating virtualization that may not yet have worked a lot with the technology.
Virtualization is beyond the "gaining traction" phase of deployment and well into "on fire." Organizations can't virtualize servers fast enough, and who can blame them? Virtualization can result in significantly lower operating costs as there is less equipment to replace, less power required, and lower heat output. Early on--and sometimes even today--some organizations believe that "less equipment" equates to "easier administration" and maybe "fewer administrators." Nothing could be further from the truth. In this post, I'll explain some of the reality behind server virtualization.
Virtualization does not equal fewer servers. This is an important myth to dispel early on. In the previous paragraph, notice that I used the term "less equipment" and not "fewer servers" when I described a benefit of virtualization. In reality, virtualization can result in more servers since it becomes so simple to deploy new servers. When you're talking about virtualization, you also need to be careful with terminology. The term "server" can mean a physical piece of hardware, but when it comes to virtualization, a server can just be an instance running on a virtual host such as VMware, Xen or Virtual Server. People often call these kinds of servers "VMs","virtual machines" or just virtual servers Back to the topic, after you consolidate your physical equipment, you may be left with a fraction of the hardware you once had, but mayhave increased the number of servers--VM-based--you're supporting. After all, a single virtual host can run dozens of virtual machines, depending on the expected workload.
Now that we've established that, in many cases, the number of servers that need to be managed doesn't decrease with virtualization, it's important to note that these virtual servers still be managed as if they were physical machines. They still need to be backed up; they still need patches installed, etc. I spoke with people in one very small organization that did not realize that this was the case and thought that the virtualization software did it all (which it wasn't doing). Of course, there are solutions out there that do help to manage virtual servers from these perspectives, but many organizations are in the early stages of their virtualization efforts and have not yet taken advantage of these solutions.
When it comes to hardware reliability, virtual hosts may need to be beefier and better supported than their standalone counterparts. Of course, we all want all of our servers to operate 100% of the time, but when funding is tight, need to make financial decisions regarding support. Our virtual hosts in my organization are covered by 24x7x4 hour contracts while other hardware may have next business day support, depending on its use. With virtualization's "lots of eggs in a single basket" approach, the reliability of and time to repair the underlying hardware is of critical importance. Of course, if you've moved beyond direct attached storage and are using a SAN, you may have better availability features, such as VMotion, that somewhat mitigate this point.
Virtualization can reduce expenses. Like I said earlier, less hardware generally means less outlay of cash. And, with rising energy prices, being able to significantly reduce hardware sprawl becomes even more appealing. The same holds true for cooling costs. If you reduce the amount of hardware, you don't need as much cooling and that further reduces energy costs.
Server virtualization can improve services. As long as organizations understand that virtualization doesn't necessarily mean that some IT staff can be let go, virtualization can be a great boon as it can reduce to minutes the time it takes to deploy a new server. Working from templates and base images, server administrators no longer have to wade through a full OS installation or wait for a new server to be Ghosted.
I most cases, administrators should view a virtual server just as they would a physical server. It's an entity that needs supervision and management in order to remain functional. Although virtualization provides amazing benefits, make sure to separate reality from the hype before you undertake your own projects.