Virtualization is becoming more and more popular all the time, and if you don't know much about this technology, I would highly recommend you begin learning. In fact, if you are a technology worker, you ought to have some sort of virtualization software installed on your computer right now. Testing, practicing, learning, all of these are made easier with a virtual machine that allows you to try out ideas without affecting your daily work.
One of the advantages of virtualized servers is that they can be moved from one set of physical hardware to another. If you find that your virtual machine (VM) is not receiving enough resources from the host, you can move it to another less busy host, and improve performance. What's even more amazing is that you can move this VM while it is in use. In fact, your clients may not even notice that the VM has migrated to another host, even while connected. To me, that's absolutely amazing.
The way it works isn't important, but how quickly and smoothly it moves is important. VMWare and Hyper-V both support this live movement, and this might be the place we find the next race to speed up performance from software vendors. According to this article, the latest version of VMWare can move hosts five times faster than Hyper-V. Whether that's true or not, I think it's good that there is competition in this area, spurring innovation and research into ways that we can improve hypervisor performance.
Improving that performance will lead to more applications for virtualized machines, including databases. I know plenty of people that are running SQL Server on a virtual host, and doing so quite successfully. It can be done, just be sure you do a little planning and think about how you virtualize your server. Also be aware of the limitations that exist in the hypervisors and don't assume every SQL Server instance makes a good candidate.
As always, test before you make the move, and be prepared for issues to come up, but don't be afraid of making the move to virtualized database servers.
Steve Jones
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