Virtualization is a big buzz word in technology. New for some, old hat for others, it is always changing and evolving. A lingering question for many people, though, is….just what is it? Others wonder how it could possibly help their company, a place that doesn’t have a bottomless wallet or 500 servers. I’m going to try to answer those questions and maybe stir up some others.
Virtualization isn’t Lawnmower Man. That is virtual reality. The word “virtual” indicates something that isn’t real, but obviously the functions performed by servers are real, so how does that translate into computing? Basically a type of software, called a hypervisor, interfaces with hardware to provide functionally to representations of physical machines. The hypervisor presents resources (processors, memory, etc) to virtual machines based on need. The virtual machines are actually just files, each with its own functioning operating system, that run processes just like any other computer. Each virtual machine is its own entity, thinking that it has a processor, memory, hard drives, and network cards.
So, why do it? Old ways of provisioning meant that one function equaled one server. This stems from technology that could only support one function on a group of hardware components. Processors were slower, memory lower, hard drive space smaller, and servers much taller. Ok that was bad…sorry. When you buy a server to perform a function today, little thought goes into the hardware, since you can’t get a slower processor for something like a file server. The choices are usually fast, faster, and truly expensive and unnecessary. The same thing goes for hard drives. Most businesses will never use all of the 400GB of hard drive space that came with their server. This is the problem known as server sprawl. The processor power, memory, and unused disk space from one physical server cannot be used in a different server, so you end up buying another piece of underutilized equipment. This creates more power consumption, floor/rack space, management time, support costs, etc.
This is the point where virtualization begins. There are plenty of hypervisors available, but since VMware is the leader in the industry, and I’m also certified, I’m going to use it as the product of choice here. To reduce server sprawl, indirect costs, and most likely improve performance over aging physical servers, we’re going to consolidate resources onto one or more virtual machine hosts. If 10 servers run at an average of 5% CPU utilization, it is easy run them all on one server at ~50% CPU. The same goes for RAM, disk, networking, etc. VMware has optimized drivers and “tricks” to increase the consolidation ratio (virtual to physical with a goal of at least 8:1) so that you can over-commit RAM instead of barely scratching it. It’s also possible to go directly from a physical machine to a virtual machine, a “P2V”, so that you can keep the applications, data, etc. as it exists today and instantly give your server a hardware upgrade. Now that you have a VMware ESX server, it is possible to change hardware configurations on the fly. Some items, such as memory, require the virtual machine be powered off, but you no longer have to purchase memory, wait for it to arrive, and then schedule downtime for a physical install. I can add RAM to a virtual machine in 15 seconds on top of the time it takes to shut down and start up again. Need more disk space? New hard drives can be added on the fly while the machine is still running, and existing drives can be expanded with basically a reboot–going back to the 15 seconds or so to add some new virtual hardware.
You’re probably thinking that all of this sounds fancy, but how do you know if it will work for your business? My answer is that it most likely will. VMware has a tool that is provided to trained, authorized partners, like InterWorks, to analyze your environment and not only tell you the performance and utilization of every computer on your network. Capacity Planner will indicate the potential number of ESX servers required to support your environment. Of course, you and I would talk about redundancy and uptime requirements, but the tool certainly shows how the virtualization of your environment can begin.
…..To be continued.