As for the choice of virtualization software, you can try them all out on a lab system. Armed with several hard drives, you can install VMware ESXi, Microsoft Hyper-V, Citrix XenServer, or Red Hat RHEV on one disk apiece, and simply boot to one disk at a time to see which software fits your needs the best. All of these packages are available either as free instances or as trials with evaluation periods of 30 or more days.
3. Build Your Own Shared Storage
When you're working with virtualization frameworks that have multiple physical host servers, you'll need some form of shared storage to fully realize the benefits of virtualization. For instance, if you want to be able to migrate virtual servers between physical hosts, the storage for those virtual servers must reside on a shared device that each host can access.
Some virtualization arrangements can address a variety of storage protocols, such as NFS, iSCSI, and Fibre-Channel. For lab or testing purposes, you can simply add several hard drives to a Windows or Linux system, share them with NFS or iSCSI, and bind your lab servers to that storage. If you want a more complete "homegrown" approach, give open-source storage options, such as FreeNAS, a try. This software offers a simple way to add a variety of storage to a lab or production network, using cheap hardware.
4. Spend Time in the Lab
Armed with some form of shared storage and at least two physical host servers, you have the basis of a full virtualization platform ready to go. If you're evaluating several different packages, try each of them out for a week or so. Make sure to step through all of the features important to your needs, such as live virtual server migrations, snapshots, virtual server cloning and deployment, and high availability.
You may also have the ability to try out production workloads in the lab to get a feel for how the setup will perform in the real world. You might build a database server and use a backup of a real data set to run some reports, or use a Web server benchmarking tool to measure the performance of a Web application server. This practice will not only familiarize you with the day-to-day functions of the virtualization platform but also give you some insight as to what resources your virtual servers may need when they enter production.
5. Keep the Lab, Even When You Begin Production
After all this, you've likely settled on the arrangement you want to use in production. You've gotten a feel for the management tools, and you've mapped out how you want to proceed with the real deal. Now is not the time to dismantle the lab, however.
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