Virtual World

Thanks to the XenSource acquisition, Citrix has inherited one of the most advanced technologies for open source virtualization: however Xen is released with GPL license: everyone can use the code and make competitor products, in fact some big companies in the sector and some Linux distributors have already leveraged this opportunity. How are you planning to compete with those players and how do you judge the business model related to the free software?

Xen has multiple routes to market, making it one of the most strategic products in the industry. With the top twenty players in the market continuing to invest in Xen, there is the added benefit in terms of continued support and investment.

Furthermore, the fact the Xen is open source means that the security community can work to ensure that it is secure by developing and enhancing the product continually.

At the same time, it’s important to realise that Xen is an engine, not a car. In order to be able to “drive” Xen, you need to place it in a vehicle. The reason we created Xen was to address the need for a fast, free and compatible hypervisor. This in turn creates a market opportunity to sell enterprise software products as well as the opportunity to deliver a fast hypervisor globally. Essentially, we are providing the platform to build not only a powerful car but all the management facilities to develop a high powered virtualisation solution; XenServer platinum edition is one such example.

To support the global hypervisor strategy, Citrix has also collaborated with Microsoft for three years. The purpose of this collaboration is to ensure that the hypervisor is fast, free, ubiquitous and compatible; recent months have seen Citrix’s XenServer become compatible for Microsoft Hyper-V too. This will soon be the case with every hypervisor, no matter how it is distributed. The only exception is VMWare.

More importantly, the recently launched XenDesktop, Citrix’s desktop virtualisation solution, has the ability to leverage the hypervisor that is delivered in XenServer or Hyper-V and is supported by Microsoft, challenging the business model that was based on an expensive old model.

Among the characteristics of Xen there is paravirtualization in a Linux environment. Some benchmarks however highlight gaps in performance in the Windows environment. Is this a real problem? Will you develop this issue?

Paravirtualisation (ParaV) is a technology that was designed for vendors to enlighten offerings so that they can run optimally on the hypervisor. The technique delivers good performance benefits when they are running on a product such as Xen; for example Microsoft Server 2008’s Hyper-V is a ParaV hypervisor. All current and future generations of X86 operating systems are immediately able to benefit from the powerful architectural advantages of Xen. How do we deal with legacy non virtualisation systems within linux or Windows? In case of Linux, distributors have released ParaV extensions for previous versions. For versions earlier than that, powerful enhancements available from Intel and AMD are available in their virutalisation enhanced processors Intel VT/AMD V.

Xen is continually optimised for the latest generation of processors and the Xen project does contain enlightenment for legacy windows. This is one of the key areas of innovation for Citrix and as a result, Windows performs optimally when virtualised on Citrix Xenserver. A good example is the performance of XenApp (formally Presentation Server) on top of XenServer. Xenserver can sustain a workload 76% greater than any other leading virtualisation vendor in this situation, making it the platform of choice for virtualising windows in enterprise situations.

Some people complain of a delay in the implementation of functionalities such as high availability and load balancing in your products. When will you implement these features? Also do you think they are important in order for to compete with other players?

High availability will be available in the forthcoming release of XenServer, which will be available before the end of the year.

In terms of dynamic web balancing, Citrix offers the leading load balancing appliance, Netscaler. It is important that users of virtualisation think that powerful features such as these need to be implemented within the virtualisation management layer / hypervisor. Netscaler has ability to load balance across native and virtual workloads; we even have instances of customers using Netscaler to dynamically provision virtual machines and native workload instances in order to respond to application layer SLAs and dynamically changing needs in the datacenter.

What type of clients is Citrix Delivery Center targeted at?

Citrix’s family of enterprise products, which make up the Citrix Delivery Center, offer a compelling suite of application delivery capabilities, spanning from presentation virtualisation to application virtualisation to server and desktop virtualisation, as well as delivery of web applications too.

Xen is a very good product for paravirtualization. What about its performance in the Windows environments?

XenServer achieves comparable performance for Linux in windows workloads. All guest operating systems on XenServer operate close to their optimum level of performance. Customers choose XenServer for the strong performance with windows workloads.

Several manufacturers are working on clustering solutions for Xen. Will Citrix invest in this sector, perhaps through other acquisitions, or will Citrix prefer to work internally on these developments?

Since release 3.2 of XenServer we have supported a powerful clusturing regime. However, XenServer also has a powerful integration suite that allows it to directly manipulate enterprise storage shared between multiple services to achieve other virtual infrastructure capabilities. Cluster file systems in context of virtualisation leads to the inability to scale, as we have seen in other vendors products.

XenServer can take advantage of provisioning, cloning and HA backup so that customers using products from HP and Dell, as well as other key Citrix customers, can take advantage of powerful capabilities built into latest arrays to provide all storage related functions for virtual machines including back up/disaster recovery, as opposed to implementing a new software layer on the host.

All cluster file systems have significant scalability limits, performance impact and limits the types of storage that users can deploy for their infrastructure. XenServer can take advantage of all forms of local storage but still provide a consistent storage interface to the virtual structure.

What kind of support do you offer to the Xen virtualization community?

Xen development community supports itself through collaborative exchange of code and user forums. The community works to remedy bugs and issues. This is an open source effort and not product related, as each vendor is responsible for its own product support. There are two forums specifically for product support – open XenServer forums and Citrix 24/7 support. Where the technology is embedded in leading hardware from Dell, HP and NEC, vendors offer support directly.

Is there already or will it be in the future some collaboration between Sun’s OpenxVM.org community and yours?

Sun simply uses Xen hypervisor in its own project, incorporated into Solaris. If there are any specific needs related to Solaris, we’d expect to see patches from the community. Its Sun’s own project and product – we don’t build other people’s cars.