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Red Hat users eye Xen-to-KVM move

Support for KVM server virtualization has grown, but users who make the move from KVM to Xen face a potentially complex migration process and political minefields in the data center.

BOSTON – Red Hat users say they plan to kick the tires on Red Hat KVM virtualization, but even those on board with Red Hat's shift from Xen to KVM technology may face a tricky migration process for technical and political reasons.

For more on Red Hat Enterprise Virtualization and KVM:
Red Hat Summit 2010

How will KVM virtualization affect RHEL Xen users?

Linux community turning away from Xen virtualization

 Red Hat Summit attendees attending a hands-on lab demonstrating the process of manual migration that's currently the default in Red Hat Enterprise Virtualization (RHEV) 2.2, which was released this week, encountered a manual process they said was less than straightforward.

Depending on the infrastructure, the manual conversion process may require users to change the MAC addresses of virtual machines (VMs), change the default kernel on all guests and hosts, rename all references to storage disks, shut down and restart systems and perform many commands.

"We have the expertise to do it in-house with a week or two of a full-time employee's time," said Kristofer Francisco, an IT professional who requested that his company not be named. "It's not that it's not feasible, but it's definitely not just a click of a button."

[Red Hat Enterprise Virtualization's manual migration] is definitely not just a click of a button.
Kristofer Francisco,
IT professional

 A newer tool called virt-v2v which is slated for official release with Red Hat Enterprise Linux (RHEL) 6, was also demonstrated at the show. The tool pulls all the steps being demonstrated in the hands-on lab into a single command-line tool. Virt-v2v is also available in Fedora and in a child channel of RHEL 5, according to Matthew Booth, a senior software engineer at Red Hat. Booth said a user interface (UI) version of the tool may be forthcoming, but "we haven't looked at it specifically yet," adding that virt-v2v is "a very scriptable tool, so large numbers of conversions are very simple."

Still, virt-v2v requires the shutdown of the guest being converted as well as a networked storage pool separate from the source and target storage pools, used specifically for the conversion process.

Christopher Caldwell, a senior information systems engineer at an East Coast-based university, noted that Red Hat currently only supports migrations from RHEL and VMware to RHEV or RHEL. "What about SLES [SUSE Linux Enterprise Server], Novell and GroupWise? It seems like everyone throws in Windows because it's everyone's cross to bear, but there's nothing about converting Citrix XenServer or SUSE – it seems like [virt-v2v has] a very limited use case."

Political obstacles to Red Hat KVM virtualization moves
Caldwell said that aside from the technical process of migration, converting hearts and minds will also be easier said than done in his shop, where there some IT administrators are loyal to EMC and its server virtualization subsidiary, VMware.

"The storage guys have all been to EMC and VMware training classes and tend to push back on anything that's not EMC. I'm sure that's true of anybody; they push their specialty."

Tom Becchetti, a server and storage engineer at a large manufacturing company, said prior to the conference that application vendors also often dictate the choice of server virtualization platform. Becchetti said his company uses Oracle databases for mission-critical applications, and Oracle will only support virtualizating its application on its own version of Xen. "It's more important for us to keep Oracle happy than to keep RHEL in our environment," he said. Oracle Corp. has also pushed its users to standardize on Oracle Enterprise Linux.

Caldwell countered that Red Hat has said it will "step up" to support Oracle running on RHEV. What happens if there is an Oracle-specific problem? "That's a good question," he said.

Even for users who find Kernel-based Virtual Machine (KVM) technically appealing, IT investment at most shops has already picked a date to the dance. According to the 2009 Virtualization Decisions survey some 64% of respondents said VMware ESX or VMware Server is their primary virtualization platform, followed by 6% who chose Microsoft's Hyper-V. Just 3% of respondents said that RHEL-based Xen was their primary server virtualization platform.

"There's definitely some pushback" among clients that have already set up business continuity and data backup plans around VMware and understand the management tools associated with it, according to Endosys systems architect and Red Hat consultant Ivan Makfinsky. "Red Hat isn't new but it's new compared to VMware."

"One of the questions that has to be asked by any company that's already invested X amount of dollars and training time in VMware is, what is the incentive to move to KVM?" said Red Hat reseller Frank Basanta, the director of technology at New York-based Systems Solutions.

Navin Thadani, the senior director of Red Hat's virtualization business, said this isn't a new story line for Red Hat. "Nobody's minimizing the 'soft issues'" of doing a migration to KVM, he said. "That's why it's not going to be implemented the day after it was introduced. But at Red Hat, we are where we are because we helped the enterprise move away from proprietary [operating system] architectures; think that was a cakewalk? We know how to do this."

Beth Pariseau is a senior news writer for Write to her at

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