Citrix hopes to bolster the uncertain prospects of the Xen hypervisor by making its free XenServer product entirely open source. That is even though the company expects much more of its future server virtualisation business to be based on Microsofts rival Hyper-V hypervisor than XenServer. But by bolstering Xen today, Citrix is boosting Hyper-V for tomorrow.
XenServer consists of the open-source Xen hypervisor, wrapped in proprietary Citrix code. A public comment from a senior Citrix executive has revealed that soon this outer wrapping will also be open source.
Xen faces tough competition and thinning support
Among enterprises, Xen is still the second most popular hypervisor, behind VMwares dominant ESX/ESXi hypervisor. Indeed, Xens market share, currently around 1520%, is increasing. But that growth will soon be reversed because Hyper-V is becoming much more competitive. With Microsofts clout behind it, Hyper-V will certainly push Xen into third place within the next two years.
Meanwhile, for various reasons, vendor support for Xen has waned. Linux supplier Red Hat has switched its focus from Xen to the rival open source KVM hypervisor because, unlike Xen, KVM is part of the Linux kernel. IBM has also switched from Xen to KVM as its principal public cloud platform.
Due to Oracles acquisition of Virtual Iron last year, and its imminent purchase of Sun, there are now only three major backers for Xen: Citrix, Oracle and Novell. Citrix has said it believes most of its future server virtualisation business will be based on Hyper-V; Oracle faces a tough battle to increase its currently tiny share of the x64 bare-metal server virtualisation market; and, as a Linux supplier, Novell may well follow Red Hats example and support KVM.
An open source XenServer will boost Xens cloud appeal
The open sourcing of XenServer is mostly being done to suit the public cloud sector, where Xen is currently the most popular hypervisor for infrastructure services. This cloud presence is important to Xens future because it could influence enterprises: to maximise interoperability with public clouds, enterprises will want to install the same virtualisation platforms on their own premises as used by service providers. VMware is trying to displace Xen in public clouds, and the handful of providers that it has recently won over have used this potential interoperability issue as a sales pitch for their services.
Xen appeals to cloud providers because it is open source, and can therefore be customised. By making XenServers outer wrapping open source, Citrix will increase that appeal. This also addresses a separate problem that service providers have all implemented Xen differently, making migration between Xen clouds less easy. The more service providers adopt XenServer, the less this fragmentation.
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