Virtualization allows the physical hardware of your machine play host to numerous operating systems. Sound complicated? It’s timeshare of the hardware of your machine.
Understanding the hows and whys of virtualization in business terms can save money and infrastructure hassles but requires a little understanding.
This article is designed for business professionals and managers who would benefit from understanding what virtualization can offer.
- The timeshare setup
- Major headaches solved
- The up and down sides
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The timeshare setup
Explaining some terms
Imagine buying a beautiful home by a sun kissed beach but you’re only going to use it for a few weeks for your holiday every year. The rest of the time it will sit idle. What a waste. You could rent it out but that’s just as much hassle. A time share is where you have rights to a property but share those rights with other people. A divided form of ownership or use rights. Now you only pay for the part / time allotment that you use.
Save money and get a dream location. You just gotta share a bit. Timeshare a bit. You don’t bear the full cost of the house but you also don’t have it all to yourself. Some people don’t share well with others and that’s ok too. This is a pro / con discussion.
In another article I use an analogy to compare a physical computer to a city. Click here to have a read.
A server is a computer. It operates in the same way a computer does. The major difference is the focus of the role. A server is there to serve all day and can serve one or hundreds of thousands of requests.
Continuing the city analogy. If you want a quiet life and not do much you can live in a small town. If you have thousands and even millions of people to take care of you need a major city. A server is the same and consequently built for big city life. People still live and work there but there are more options compressed into the same space.
As servers are usually physically bigger and often noisey (due to fans) and generate a lot of heat, they are often kept in rooms dedicated to look after them. A “Data Centre” is a building primarily looking after power to many many servers and keeping the place cool.
Servers tend to cost more than personal computers as like comparing a city to a small town, they have different jobs and the parts whilst similar in nature have to be built differently.
In the city analogy the CPU is the Government buildings, RAM are the warehouses were currently worked on documents are stored and outside the city are warehouses for long term document storage called Hard Drives. The Operating System are the set of laws the Government enact for that city.
Can also be spelt with an s as in virtualisation but means exactly the same thing.
Buying a server is not cheap. Hosting a server in a data centre is not cheap. The more you use a server the more space it takes up and the more power (CPU processing power, RAM, etc) it needs.
If you buy a server you have very physical restrictions. Whatever speed CPU is in there, is the speed. However much RAM you buy, that’s it. Hard drives are hard drives and if you need to change them are time consuming and awkward to do.
There are companies who have bought and host very very large servers. You can timeshare a bit of one saving a fortune. So there is the physical server with all the bells and whistles and you will have a “virtual machine” running on it. This virtual machine is your timeshare.
Most people at their desks or at home have their own “personal computer” and don’t need to timeshare. A server on the other hand is there to serve. It may or may not be busy.
Major headaches solved
So who manages the timeshare… this is a program called the hypervisor or Virtual Machine Manager.
Let’s start with one approach.
The host machine is what the hypervisor manages whilst there can be one to many guest machines which chat to the hypervisor.
Let’s image that the hardware has 32 CPU cores available. That is 32 CPUs available to do work. The Hypervisor can allow 4 of these to be allocated to one virtual machine.
The owner of virtual machine 1 decides one day actually I need 8 cores as the server is getting busy. Through the Hypervisor they can be allocated more without the need to buy new hardware or install a new machine.
For the hypervisor owner they only have one physical server in the data centre to manage yet there could be three servers running on that one physical box. Timeshare!
There are many flavours of Hypervisor but some of the biggest names are Hyper-V, Integrity Virtual Machines, Oracle VM, PowerVM, Virtual Box, VMware and Xen to name a few. There are more here.
Varieties of timeshare
There are different combinations and varieties and rules to timesharing. The same is true for virtualization.
Imagine our lovely timeshare building again… ahh our beach side getaway. You decide “I want to knock this wall down to give myself an infinity view of the ocean” not realising it will cause massive structural damage and affect others around you. This is where the rules and the building manager, the hypervisor has to kick in consequently there are two different ways of ruling.
Hypervisor is the boss and is actually in control of what can and can’t be done.
Full virtualization, gives the guest machines direct access to the hardware and like a good landlord is sitting there waiting and listening to all you’re doing. If you do something against the rules it can step in and make sure you don’t mess it up for everyone.
Paravirtualization is a different approach. This means, as per the diagram above, everything runs through the hypervisor. This does mean that the operating systems of these machines need to learn to work with hypervisor and not with the hardware directly.
There are also other types of virtualization available but they mean slightly different things.
Desktop virtualization is a funky way of getting a powerful personal computer. You remote control one of the virtual machines running on the server as a result if your PC blows up or is stolen… no worries, as you were doing everything on your virtual machine on the server. Expensive but secure and if you need a lot of power the server can have that easily for you.
Operating-system-level virtualisation is where one operating system gets all the hardware. It acts not only as a host machine but also allows guest machines to run on it too. Developers use this approach to test things rather than in server environments. Virtualization runs slightly differently to your desktop machine.
One really important concept to guest machines is that it is easy to take a snapshot of them therefore like a photo, you copy RAM and Harddrive usage very easily. This makes backups really easy for IT people to do furthermore you just have one file of where every program, setting and even RAM is.
This snapshot moves easily to another server with more resources which makes disaster recovery so much handier.
Snapshots are a huge part of why virtualization saves money, time and reduces risk for business.
The up and down sides
The up sides
There are many reasons but here are the usual up sides of choosing a virtualized environment.
- Reduced hardware costs as you only pay for what you need in your server.
- Saves physical space as you can have many servers in one box
- Faster server provisioning and deployment as you choose options from servers that have the hardware and the capacity.
- Disaster recovery is much simpler thanks to snapshots and the ability to move one guest computer between hardware without the server ever turning off.
- Virtualization saves significant energy costs not just because it’s only one server not three or four but the cost for cooling the room. A/C is expensive.
- Increase staff productivity because you can give them more powerful virtual machines and they can work anywhere in the world controlling them remotely.
- Virtual labs allow rental of testing environments for the purposes of testing and then turned off when no longer needed.
- Move to the cloud… as the servers don’t have to be in your building any more.
The down sides – playing well with others
Virtualization has been around as a concept since the 1960s where mainframes were too expensive to build for just one purpose. Wikipedia does a full listing.
The security concerns of sharing equipment make people nervous but in truth there haven’t been too many major leaks.