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Citrix refocuses on cloud, turns to Microsoft with XenServer 6.0

Now in beta, XenServer 6.0 sports improvements including a more integrated distributed virtual switch, but Citrix is handing enterprise virtualization management reins over to Microsoft.

With Citrix Systems Inc.’s XenServer 6.0, the company is positioning the hypervisor for public cloud service providers and looking to Microsoft’s System Center for enterprise virtualization management. The new version, slated for release later this year, also sports new features for enterprise accounts.

[Citrix is] not going to be the VMware killer.

- Gary Chen, IDC research manager

The transition to Microsoft-centric enterprise virtualization management began in June with the discontinuation of Citrix Essentials for Hyper-V and StorageLink Site Recovery for Hyper-V. In making these moves, Citrix cited overlap with Microsoft’s forthcoming System Center Virtual Machine Manager (SCVMM) 2012.

With the XenServer 6.0 beta released in early July, and in the wake of Citrix’s acquisition last month, Citrix officials are reiterating that message.

“We look at our virtualization technology mostly being oriented around cloud deployments, and cloud provider infrastructure,” said Derek Slayton, senior director of product marketing. “For virtual private cloud management…we don’t focus on that aspect of the market as directly as Microsoft does.”

Partners aren’t surprised, noting Microsoft and Citrix have been cozy for years.

“Citrix understands that they can’t do everything right now to be competitive, and by that I mean go head to head with VMware,” said Jon Spallone, lead integration architect at Convergence Technology Consulting. “Instead of trying to redevelop the wheel, it makes more sense for Citrix to just go ahead and use what’s in most enterprises today. Typically…if users are running something other than vSphere, most are going to have [Microsoft] System Center.”

According to Gary Chen, IDC research manager for enterprise virtualization software, these moves indicate "a realization that if they want to expand XenServer more seriously as a server virtualization solution, they’re not going to be able to do it on their own. They’ve been doing it on their own for quite a while, and while they’ve had some amount of success, they’re not going to be the VMware killer.”

Still, Chen is happy to see Citrix move ahead with XenServer. With top executives Simon Crosby and Ian Pratt leaving Citrix, many questioned where XenServer was going.

"This is kind of like the second life of XenServer, to have it live on in a cloud incarnation instead of just virtualization,” he said.

Pulling back on enterprise storage integration
With the 6.0 release, Citrix is also scaling back its XenServer StorageLink enterprise storage management program and removing array-based replication management from its Site Recovery feature.  

StorageLink, introduced in 2009 with XenServer 5.5, provided a means of creating logical unit numbers (LUNs) as needed to support required virtual machine (VM) disk files, while native storage management requires the LUN to be pre-created. The program still runs, but with a drastically scaled-back partner list; now, only EMC Corp.’s Clariion, NetApp Inc.’s FAS and Dell Inc.’s EqualLogic arrays remain in the program. Other arrays can still connect to XenServer via Fibre Channel, iSCSI, NFS, or StorageLink through SMI-S, which is also in line with Microsoft’s plans for storage integration under SCVMM 2012.

The pullback on StorageLink may have been because Citrix couldn’t build the ecosystem, Chen said.

“I think technically it was a neat thing, but I think they probably just couldn’t get the attention of a lot of the partners,” he added.

Site Recovery will still manage the restart of multi-VM applications through the integration of vApps with the 6.0 release, but users will have to coordinate array replication with the replication of VM images separately.

In the meantime, users like Mike Nelson, systems administrator for an insurance company in the Midwest, still wonder why XenServer has not included anything akin to VMware’s Storage vMotion.

“I just don’t understand why we can’t get that capability,” he said. “It removes so much administrative overhead and headaches when machines have to move from one storage platform to another without an outage, without downtime.”

Citrix’s Slayton said a similar feature is on the XenServer roadmap, but it is geared more toward public cloud providers using large farms of local storage directly attached to servers.

Brushing up virtual switch, workload balancing and more
XenServer 6.0 is not without improvements for enterprise use. The distributed virtual switch (DVS) first introduced with XenServer 5.6 SP1 last year is now the default option for networking within XenServer. Previously, networking had primarily relied on Linux-based network bridging, which was more tied to physical than virtual resources.

According to Convergence’s Spallone, the DVS improvements will help clients that need to dedicate more than two network interface cards (NICs) to a VM. Previously, that was accomplished using “more exotic” methods such as physical NIC bonding and virtual LAN tagging, but will now be possible natively within the virtual switch, he said.

XenServer’s workload-balancing feature will now integrate directly into XenServer, as opposed to requiring a separate Windows-based appliance for dynamic memory management. Nelson found this the biggest improvement in the 6.0 release.

“We don’t have to do patching and upgrading on the Windows OS, which is what the original Workload Balancer needed,” he said.

Finally, the ability to import and export VMs using the Open Virtualization Format has been improved, with better reliability during the conversion process, users say. In the past, “sometimes you’d get corrupted disk files, or they wouldn’t boot,” Nelson said. “It was a 50-50 shot whether the VM was actually going to work.”

With the ability to more easily import and export VMs between hypervisor formats, users say XenServer 6.0 opens the door to move at least some workloads onto XenServer.

Phil DeMeyer, an information technologist at an early-childhood education program in the Midwest, said the importing improvements mean he may consider moving his XenApp environment off a VMware back end.

“I have good reasons to stay with VMware,” he said. “But at the same time, some of our main products are Citrix products…and there are very good reasons to run those on top of XenServer. It just makes administration easier.”

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

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