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Cloud computing provider chooses XenServer over Xen

Now that commercial options like the XenServer hypervisor include built-in management features, cloud computing providers may choose out-of the box offerings over open source Xen.

Today most cloud computing providers use the open source Xen hypervisor as their virtualization backbone. But users may increasingly gravitate toward commercial options -- some of which, in fact, are based on Xen's open source code -- such as Citrix XenServer. These offerings provide out-of-the-box capabilities and attractive management features that users have deemed worth the price. As more providers move into the cloud, they too may choose a packaged hypervisor that facilitates management tasks and alleviates the burden of writing code with open source Xen.

Consider Singapore Computer Systems (SCS). A channel partner of Citrix Systems and the managed service provider for grid computing services for Alatum, Singapore's largest commercial grid computing platform, SCS recently chose Citrix XenServer virtualization and support for its Platform as a Service offerings.

Why XenServer?
SCS' grid infrastructure is built on a scalable and redundant architecture and promises 99.9% availability. It has more than 2,400 CPU cores and 16 TB of usable storage to support thousands of customers simultaneously, according to Lim Jee Yen, the director of grid computing at SCS. Thus far the company has deployed XenServer on 200 physical servers with between four and eight virtual machines per physical server, Yen said.

SCS chose XenServer over open source Xen primarily because it wanted a server virtualization product with features and benefits built in, Yen said via email.

One such benefit of XenServer over open source Xen is the management console, XenCenter, which gives SCS control of and visibility into its virtualized resources, Yen said.

SCS could not disclose how much it invested in Citrix, but the company uses XenServer Enterprise Edition, which starts at $1,599 for an annual subscription license per dual-socket server. So, on 200 dual socket servers, the total cost of XenServer Enterprise edition at list price would cost the company about $320,000 (in U.S. dollars).

The price of XenServer was cost-effective for SCS because of the hypervisor's included features -- such as shared-storage repositories and server resource pools, live re-location, high availability and disaster recovery – all of which are standard features of XenServer Enterprise, Yen said. "XenServer helps in accelerating our speed to market, besides its strong support and training services from Citrix, which are all important to the Alatum consortium," he said.

XenServer suits cloud
SCS could also integrate XenServer with its existing management software through programmable Web services-based application programming interfaces (APIs) and scripting technologies. Further, XenServer also supports management APIs based on the Open Virtualization Format (OVF) created by virtualization providers and accepted by the Distributed Management Task Force, or DMTF.

Standards-based virtualization is important to cloud providers because eventually it will enable seamless movement of applications and data from one cloud environment to the next, Charrington said. OVF, for example, standardizes the means to package and distribute virtual machines across different platforms.

SCS also found Citrix's support of cloud providers and its plans to create an ecosystem of cloud-based partners attractive. "This open, partner-friendly strategy helps partners like us to offer value-added security, high availability and multitenant services that allow our customers to benefit in the long run," Yen said./

SCS's need for a commercial virtualization platform and its willingness to pay for built-in features serves as an example of what Gartner Inc. VP and distinguished analyst Tom Bittman recently cited as a trend as cloud platform providers become more ubiquitous. "They won't want to write their own software using Xen; they will want to buy software, and that is where companies like Sun Microsystems, [VMware and Citrix] could make a play," Bittman said.

No hypervisor leader in cloud
Still, despite Citrix's benefits, no vendor has yet made a name for itself as the de facto virtualization platform for cloud computing, and no cloud software suites have been designed for cloud environments. This stands in contrast with enterprise IT environments using virtualization (i.e., VMware Virtual Infrastructure). "Neither commercial nor open source virtualization platforms provide a complete solution for up-and-coming cloud providers, so companies trying to enter this market have significant development and integration hurdles to overcome," said Sam Charrington, the vice president of product management and marketing at the St. Louis, Mo.-based cloud application platform provider Appistry Inc.

That said, cloud platform providers typically choose either open source or commercial virtualization technologies based on factors such as the speed with which they need to get up and running, Charrington said.

"In cloud computing and virtualization," said Charrington, "choosing between open source and commercial offerings means trading off between speed to market, features, support and development costs on the one hand and up-front licensing fees on the other. In a fast-moving market like cloud computing, many organizations will choose to jump-start their efforts by going with a commercial offering," said Charrington, who works closely with cloud providers.

During VMworld 2008, VMware introduced its vCloud initiative, aimed at helping managed service providers become cloud platform providers. At the same time, Citrix announced the cloud platform Cloud Center, or C3, along with the release of XenServer Cloud Edition.

For companies with data centers, the major benefit of outsourcing to cloud environments is that it gives them a way to scale up quickly without investing in new hardware and software. Many cloud computing providers like SCS charge customers on a per-usage basis.

"There might be areas of my business I don't have economies of scale for, so I can outsource certain portions of the business," said, Bittman. "For example, SmugMug [a photo-sharing website] uses Amazon EC2 for peak loads and keeps the fixed-load stuff in-house," said Bittman.

Let us know what you think about the story; email Bridget Botelho, News Writer.

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