It is clear that VMware is facing significant challenges from at least four different sectors. Citrix, Microsoft, the Xen community and Red Hat are all hoping to push the VMware off of the throne and assume the title of "King of Virtual Machine Technology." The stiff challenge is causing the hypervisor itself to become a commodity and, as my colleague Greg Zwackman pointed out in a recent report "Virtualization Software: Market Sizing and and Forecasts Overview," suppliers will be forced to look to other segments of the overall market for virtualization technology for increased revenues and profits.
VMware today holds the lions share of the overall market for virtualization technology including products for application virtualization, desktop virtualization, server virtualization, management of virtualized environments and security for virtualized environments. It counts on the help of partners, such as Cisco and EMC, for help in the areas of network virtualization and storage virtualization. It has a broad ecosystem and strong marketing.
Microsoft, somewhat late to the market, has decided to build upon its dominant position in the operating system market and has used a tactic that has been very successful in the past - simply fold virtualization technology into its operating system products and offer the package at price not much different than the operating system alone. It is not as strong as VMware in the capabilities of its virtualization software, but is improving rapidly.
Citrix, leader in the access virtualization market, has been expanding its product portfolio to cover access virtualization, application virtualization, virtual machine software (hypervisor), some network virtualization categories and management of virtualized environments through both in-house development and acquisition. It also has a broad ecosystem and counts on others for other forms of network virtualization and storage virtualization. Citrix is trying to walk the fine line between being a good friend of Microsoft and being considered a member of the open source community. It has strong ties to Microsoft and offers tools to manage both XenServer and Hyper-V environments. Recently it launched "Project Open Door" to use its capabilities to help VMware customers move to either XenServer or Hyper-V.
Red Hat, formally a strong proponent of Xen, appears to have not been pleased with Citrix's acquisition of XenSource because it acquired Qumranet, the source of KVM technology. It is currently moving on a trajectory to replace Xen with KVM in its offerings. I'm sure that they'll continue to support Xen in their product offerings, however. Recently, Red Hat inked a deal with Microsoft that means both companies will test and offer some level of support to integrated Hyper-V/KVM environments.
Xen community is an interesting wild card in this tournament. Xen is a standard part of most Linux distributions. Suppliers such as Novell/SUSE, Oracle/Sun and others are offering Xen-based environments. The strong competition between and among these players is resulting in a rapid commoditization of the hypervisor, standard file formats for virtual machines, management interfaces and a number of other areas of interoperability.
While it is impossible to pick winners and losers in this battle because everyone will win somewhere, it is clear that VMware is facing the need to rapidly innovate.