Regardless of which VM platform is used -- there is some mix-and-match in the enterprise today though it poses specific management challenges -- Gartner analysts say there is a dearth of mature management tools for virtualized systems.
"There's a disconnect today," said Wolf, noting that a recent forum Gartner held for more than a dozen CIOs overseeing their organizations building private clouds, more than 75 percent said they were using home-grown management tools for things like hooking into asset management systems and ticketing.
Nevertheless, Gartner is urging enterprises to put together a long-term strategy for the private cloud and brace for the fast-paced changes among vendor and providers that will bring new products and services -- and no doubt, a number of market drop-outs along the way.
But this private cloud planning will involve updating procurement and change management processes used internally today, as well as figuring out which applications are most suited to be virtualized. Starting off with file and print and simpler applications not considered mission-critical is a good way to start. "some applications can't be virtualized because they have special hardware requirements," Wolf said.
For example, Paul Rizzo, GlaxoSmithKline's infrastructure business partner, end user infrastructure services, said the pharmaceuticals giant has found that Microsoft SharePoint does not run well in VMware.
For the long-term, Gartner cautioned businesses to make sure that future requests-for-proposal to software vendors stipulate that applications support virtualization is needed, Wolf also noted in one session that there is significant complexity in virtualization mobility, moving a VM from one hypervisor to another.
"Multiple hypervisors in the data center might need different configuration management tools," he pointed out. Sometimes enterprises in separate locations or business units are deploying different vendor hypervisors, which "can be problematic for failover, and a challenge for change control." But he noted that VMware's high licensing costs and restrictions on per-VM use in the cloud, mean IT managers may want to keep their options open to consider a switch.
Virtualization requires an entirely new way of thinking about networking, said Gartner analyst Mark Fabbi. "Virtualization changes everything, how we look at server I/O, how we deal with branch offices and disaster recovery."
Gartner reckons in virtualized environments there is "25 times more bandwidth coming from the same physical footprint," and the server I/O needs to be moved from 1G to 10Gbps, Fabbi said. "40G output is on the horizon in the high-performance blades," he noted. "The idea of 40G I/O off the servers isn't far-fetched."
One of the main drivers for all this "clearly is VMware," he said, noting that virtualization's "voracious appetite" is seen in VMware capabilities such as Vmotion. "In a virtual environment, things are shifting around." The rippling effect of all of this is that the top of rack switch will need to be pushed from 10G to 40G, using technologies like Infiniband. There may be savings in consolidating I/O, but "the challenge is in the rack," he said.
Virtualization is prompting a shift from a classic three-tier architecture to two, Fabbi said, saying the future network architecture for all this is more focused on Layer 2 than Layer 3. The newer fabric-based architectures from HP, the VCE Cisco alliance with VMware and EMC, and IBM -- in addition to any decision to "roll your own" -- should be evaluated, he said.
But data centers may still have "multiple domains," he said, for instance, "A VMware domain and a Hyper-V domain. In large organizations, you may have multiple domains. We don't think it will be totally homogeneous."
Read more about cloud computing in Network World's Cloud Computing section