Server Virtualization? I thought this was a blog on Fly Fishing…
Sorry, you are in the right place, just a change of pace to go along with my interests (both professional and not).
In my current position as a Systems Administrator my primary responsibility is maintenance of the virtualization infrastructure. Now, if you are here as a fly fisherman I’ve just spoken Greek, so I’ll try and translate. Most people have a visual idea of what a computer is, and servers really aren’t any different. The biggest difference is that they tend to be in racks (so they are long and thin), and don’t have monitors, keyboards, etc. For as long as servers have been around you had one server with one operating system on it. This meant when you need a new server for a new purpose you bought one (at a cost of thousands of dollars), and then install the operating system and the necessary software. Some shops would try to prevent this “server sprawl” by loading multiple applications on one server with sometimes disastrous results.
About 15 years ago a company named VMware came out with what is called a hypervisor. A hypervisor allows you to run multiple operating systems (thus multiple servers) on one piece of hardware. At the outset the hypervisor wasn’t great but it did the job. Well fast forward to today and pretty much here is where we stand. We have two types of hypervisors. Type 1 (or bare metal) hypervisors are installed on a server before anything else and allow virtual machines (virtual servers) to interact with the physical hardware. The second type of hypervisor is a Type 2 hypervisor. This type is an application installed on an existing server allowing it to run virtual machines. Most shops use the Type 1 hypervisor for all but lab/test environments as there is no overhead for the host operating system. VMware produces both Type 1 and Type 2 hypervisors with the most common being VMware vSphere and VMware Workstation. vSphere is a type 1 hypervisor while Workstation is a type 2.
Okay, now that we’ve got that out the way, why the heck does virtualization matter? Well there is the obvious cost/benefit ratio of being able to run multiple servers on a single piece of equipment without them interfering with each other. Plus this allows you to utilize the physical server hardware more efficiently. I don’t have exact numbers but most servers run around less than 20% utilization. This means is that 80% of the server's resources are available for some other function, but are going unused. With virtualization you can get that number much closer to 80-90% by running multiple systems on the same piece of physical hardware. There are other benefits though. Most people know computers produce heat, but really don’t know or understand just how much. In the average datacenter (say 4-5 racks of systems) without air-conditioning running 24/7 most of the systems would cook themselves (literally melt internal components) in less than 24 hours. In the datacenter where I work, no A/C for one hour can result in a temperature increase of 4-5 degrees (Fahrenheit). This means there is a massive amount of electrical usage just to keep servers cool in addition to the massive electrical drain just due to the servers themselves.
So, if you could run 8 physical servers or 8 virtual systems on 1 physical box, which would you choose?
Well the normal response would be the 8 virtual servers on 1 physical server. Which is why virtualization is the fastest growing segment in the IT field. The numbers used above are the average “consolidation ratio” most companies are seeing. Where I work it is closer to 15 to 1. So 15 virtual systems running on 1 piece of physical hardware; not too bad!
Some complex math shows in the last year we saved the company I work for about $8,000 in electrical costs alone just powering the servers. This doesn’t count the electrical cost in reduced need for air conditioning with fewer heat producing servers.
So there you go, that is why virtualization matters!
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