What is Virtualisation?
Virtualisation refers to the running of one or more “virtual” operating systems on one piece of hardware. This is done by installing a very small operating system onto a bare-metal server and then creating as many virtual computers and servers as you require.1
This means that you could run an Active Directory server, a separate mail server and a separate file server all on one piece of hardware. You would still need to buy the software and licenses as in an unvirtualised scenario but the cost and administrative benefits speak for themselves.
1 Subject to the quantity of processors, memory and hard drive capacity
What are the Benefits?
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Cost Efficiency
Downloading and installing VMWare's ESXi requires only that it be registered
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Cheaper Upgrades
Add an extra processor and some more RAM instead of buying a second server
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Faster/Safer Server Deployment
Virtualising your operating system from it's existing hardware foundation on to your new server before you perform the upgrade ensures that, should the upgrade process encounter an error, you still have the old server to fall back on instead of spending hours repairing a damaged system or restoring from backups
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Faster/Safer Server Modification
Snapshotting your virtualised, healthy system before performing any changes means, should modifications have unforeseen consequences, you can roll back to the snapshot as if the changes had never been made
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Near-Instant Recoverability
Using tried-and-tested backup methods, your fully operational server could be recovered in minutes, thereby saving hours - if not days - of server rebuilding effort should a fatal operating system error occur
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Reduced Infrastructure Cost
Added costs such as cooling, electricity, network ports, floor space and rack space can be mitigated by virtualising your servers
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Fail-Over
Should you already have a second server, both servers could be virtualised on to one platform leaving the second platform available as a 'hot-swap' fail-over system



