Posted by: Eric Siebert
Eric Siebert, Virtualization
So what do a school bus, four teenage daughters, an apartment complex, a six-foot sub and a hotel have in common? They can all be used for virtualization analogies!
In a previous post I covered the basics on what virtualization is and used an analogy to describe it. I also challenged others to submit their own analogies on how they would describe virtualization and received many responses. I thought I would share a few with everyone.
The first is from Rob Bohmann:
Virtualization is like a school bus. Instead of each parent driving their kid to school each day in their car with the resulting traffic jams and waste of time and fuel or having to build lots of extra lanes on the roads, we have the kids ride a big bus that can effectively carry a lot of people. We save resources like gas and space on the highways, as well as the parents’ time.
So if you substitute the energy of gas for the energy in electricity, whether derived from coal or nukes or hydro, etc., and the congestion around schools for the space in your data center and the more efficient management and provisioning of servers, I think the analogy works well, especially for people who are not in the technology arena.
The next is from Guy Leech:
The analogy I like to use is that of a block of flats (an apartment building in US speak?) compared with a large house on the same site. It’s the same space but obviously the flats are self contained/isolated and share the utilities. The house has the same utilities but probably doesn’t use anywhere near as much due to the inefficient use of space.
The next is from Michael Nunn:
Imagine you are a parent of four teenage daughters. All your life you have wanted to provide your daughters with their very own “resources,” like their own bedrooms, their own bathrooms, their own computers, their own clothes, etc., but you just could not afford to do it.
What if I could tell you how to give them all everything they wanted and they really believed that they each had their own bedrooms and bathrooms, but in reality you only had to build one bedroom and one bathroom? You would be well within your budget, your daughters would be very happy, and you would not be using space, materials and money to build all those separate rooms.
The next is from Robbie Singh:
Virtualization is similar to utilizing the same resources without even knowing about it. For example, if one person lives in a house he uses the same resources as phone, heat, water, rent, etc. Add one more person and everything remains almost the same. This way both people benefit. It’s like adding two or more servers on the same physical server. Obviously the scale of people vs. resources is the same as physical server to number of virtual servers.
The next is from Kendrick Coleman:
Me: When you go to Subway, you know how they have those six-foot party subs?
Other Guy: Yea
Me: Well think of the 6ft party sub as your typical physical server. Every time you have to deploy a new server, you have to order a six-foot party sub. When you go to subway, do you order a six-foot party sub for lunch?
Other Guy: Well, no.
Me: Why not?
Other Guy: Because you would have a lot of wasted food.
Me: Exactly, so you would probably want five to 10 other people to help you eat that six-foot party sub so nothing goes to waste. With today’s hardware, there are a lot of wasted resources when you have to deploy a single physical server. Virtualization gives you the ability to have five-10 servers running on that one physical server concurrently so your resources aren’t going to waste. Make sense?
*Editor’s note: Who else thinks Kendrick was eating a Subway sub when he came up with this? <grin>
The final analogy is elaborate. Mike Laverick often tells it to his students.
In the past, the server was a like a very expensive hotel. It was the worst kind of hotel. It only had one big room and only one person could stay there. However, all employees, whether they were the CEO or copy-boy, had to stay there if they were away on business.
This is like the guest operating system being installed to a physical server. Half the time the occupant is out doing other things, asleep, or just lying on the bed surfing up and down the channels looking for the type of channels his wife wouldn’t let him have at home. This is like when Linux or Windows is idling and only using 5% – 10% of CPU or memory. It became considered too costly to build such hotels and filling them with one occupant was very wasteful – because they consume heat, water and power – and most of the time the single occupant either wasn’t there or was asleep!
So someone had the idea of a better hotel, one which was divided into a series of different rooms. Each could be different sizes and offer different qualities of service. It didn’t matter what one guest did in one room, as it could not affect others. This hotel had really thick sound insulation so you couldn’t hear the wedding party downstairs or the newlyweds doing newlywed things next door.
On the top floor beyond the bridal suite, were the penthouse suites which were reserved for the high rollers, specifically for Mr. Exchange, Miss, SQL and Mrs. SAP – but in other floors the rooms were barely large enough to swing a small furry animal – this is where Mr. DHCP and Dr. DNS resided. The old hotel was so expensive only people like Howard Hughes could afford a room there – but this new, more efficient, hotel cost the same to build and maintain – and everyone could find a room that was suitable for their needs – from the odd billionaire to the business man on an overnight stay before catching a flight. It also meant we had to build fewer hotels.
The other thing we discovered was when Mr. Exchange or Miss SQL weren’t around or sleeping – as they were consuming less resources – their resources could be divvied out to the residents in the hotel to improve their experience. It would be easier to get that table in the fancy restaurant, and it was quicker to get served in the bar. Finally, the old hotel model died a swift and untimely death when the economy fell off the end of a cliff. It became increasingly regarded as a luxury no company could afford. The Hotel Virtualization model ruled the roost because it offered the most flexible model of accommodating guest operating systems with their wildly different resource demands.
Mike provides a very detailed, nice explanation, but I like Kendrick’s the best as it’s simple and easy to remember, and involves food, which is something we all can relate to. So the next time you’re in a position where you have to explain virtualization to a layman, you now have some great analogies you can use.