But, first, some definitions are necessary. When you "virtualize" a computer system what you are doing is simulating that computer on another system. For example, if I was to virtualize system "A" on system "B" I would take the following steps:
a) Take a snapshot of system "A".
b) Move that snapshot onto system "B".
c) Shut down system "A".
d) Start up the snapshot of "A" on "B".
From that point on, it looks to the rest of the network that system "A" is operating as usual.
In this scenario, system "A" is a "guest system" and system "B" is the "host system". If system "B" has enough resources (CPU, disk and memory), then it could conceivably host multiple guest systems - each guest is totally unaware and unaffected by the others. That, in a nutshell, is virtualization.
The first advantage you can see from virtualization is decreased hardware costs. If I can buy one system and host many other virtual guest systems on it, then I'm saving by not having to purchase as many physical computers.
Generally, virtualization has been used to consolidate server systems. Most physical computer servers today are vastly under-utilized. The increases in hardware capacity have out-grown the demands of the software so, as a result, most servers don't even break a sweat. By combining many guest servers onto one hardware host server, you use up more of that excess hardware capacity that you've already paid for.
Today, though, we are starting to see virtualization in many different areas. Desktops are being virtualized and so are individual applications. It gets complicated but the basic idea is that virtualization makes better use of computer hardware. That means you spend less on buying new computers and you save in the "green" aspects such as power usage and cooling.
How does virtualization improve system reliability? A system that has been virtualized is essentially "hardware independent". It can run on any virtual host system. So, if a physical system breaks down, you can move the guests systems it hosts to another physical host system without any reconfiguration. There are even tools to automate the fail-over process thus providing 100% up-time.
How well does it work? It used to be that virtualization was purely done in software. You would install virtualization software on a server and it could then host guest systems. Over the past few years, though, all the major chip makers have moved the virtualization smarts down into the hardware. This has provided a huge increase in performance to the point where it is nearly impossible to see much performance difference between standard systems and virtualized systems.
Large companies are already heavy into virtualization and are reaping the rewards. Lately, though, even base-level servers are coming with the virtualization support built in to the processor. This means that smaller businesses are also positioned to take advantage of virtualization.
As of today, in addition to virtualizing most of our own internal systems, we are using virtualization technology at four of our client sites. In each case it is being used in a slightly different way but the common benefit is that all are seeing performance improvements, better reliability, and, of course, cost savings.
But, we're just scratching the surface of what this technology can bring us. In the coming weeks I'll explain how virtualization, in combination with high speed Internet, is going to radically change the way we build, install and configure systems and how that, in turn, is going to save you money while making your systems more reliable and easier to use.
Stay tuned! Please feel free to post comments and/or questions directly to the blog.
Thanks John, for the indepth explanation of virtualization. Although you had visited us to explain the concept in person, it's nice to have a source I can now go to, to pull up the explanation when we begin to start our budget process. I suspect we will be discussing the concept in more depth with you in the future.
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