VMware, Citrix, and Virtual Iron all have full-featured demos available to try before you buy. If time allows, it may be worth the effort to build test clusters for your two top hosting candidates.
Live migration is a critical element of VM cluster management; however, you'll be able to save a lot of money if your organization can tolerate brief production outages to shuffle a VM from host to host. Likewise, assess your appetite for high-availability capabilities; high availability comes at an additional licensing premium.
Finally, a warning: The VM tools in this Rolling Review made it ludicrously easy to create a virtual server. Too easy. Ensure that your virtual environment maintains the same rigor and change-control discipline as the physical side of your shop. Wanton creation of guests and fluctuating resource demands can lead to "VMotion sickness." Don't let your virtual world get away from you.
Joe Hernick is an InformationWeek Analytics contributor and former Fortune 100 IT executive.
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