Are Two Hypervisors Better than One?

There is what I call a lot of "soft" information circulating throughout virtualization nation relating to the acceptance and growth of this technology. Depending on who you talk to, and what form of virtualization you are discussing, we have either reached some level of wait-and-see skepticism, settled into a state of mature stability or cleared the decks for skyrocketing growth.

One common notion is that where VMware doth dwell, no infidel hypervisor shall tread -- in other words, VMware shops are impregnable fortresses that are happily locked into ESX and not looking for any directly competitive products. Another notion would have us believe that some portion of VMware stalwarts are open to overtures from Microsoft regarding a possible dalliance with Hyper-V, but not Citrix, whose technology they admire from afar, but don't want to invite into their virtualization living rooms, as it were.

(The more I learn about Citrix, the less I view them in this perennial outsider's role, but that is a topic for another day.)

At any rate, a recent reader poll conducted by Enterprise Strategy Group analyst Steve O'Donnell in his "The Hot Aisle" blog puts this issue in an interesting perspective. In a late September poll he did of his enterprise readers, O'Donnell found that quite a few of them were willing to swing with more than one steady hypervisor partner.

To be specific, he found that:

• 44 percent of his readers currently use two or more hypervisors.
• 16 percent use three or more.

He posits four possible reasons for this scenario:

1. Licensing fees for the proprietary products are driving enterprises to adopt a second free product .
2. Vendor support arrangements are driving enterprises to support multiple stacks.
3. Enterprises have poor technology set management processes and are not optimizing their software portfolios.
4. The increasing maturity of Xen and Hyper-V is grabbing enterprise attention and wallet share (a "fact," O'Donnell declares), but VMware is not being displaced where it exists.

In support of his perspective, O'Donnell asserts, "My best guess is, it's likely to be a combination of 1,2, and 3." It would be folly to entirely discount possibilities 1 through 3, but I am most intrigued by number 4, and I am looking into actual instances of VMware being displaced. I look forward to sharing that information with you in the near future.

Question: Under what circumstances does it make sense for companies to deploy two or more hypervisors?

Posted by Bruce Hoard on 12/01/2009 at 12:48 PM