VMware is still the only virtualization vendor whose hypervisor meets every enterprise requirement, but rivals Citrix, Microsoft and Virtual Iron are closing in on that goal, according to research by the Burton Group.
VMware, long the market share leader in x86 virtualization, offers 100% of the features required to run enterprise-class, production workloads with the vSphere hypervisor.
Citrix XenServer and Virtual Iron are nipping at VMware's heels with 85% and 83% of requirements met, respectively, while Microsoft's Hyper-V lags behind with 78% of requirements met.
The Burton Group evaluates hypervisors based on an extensive list of criteria within the categories of high availability, live migration, memory management, networking, storage, security, compute, paravirtualization, management, power management, and licensing and support.
The analyst firm presented its research in a teleconference this week to help customers figure out which hypervisors meet their needs, and which features are truly important as opposed to simply being "marketing checkboxes."
"Hypervisor vendors would all have you believe they are better than the other guy, but their product data sheets never tell the whole story," said Burton Group analyst Chris Wolf.
The Burton Group divided features into three categories: those required to operate production workloads; preferred features that are important but not required; and features that are simply optional.
For example, high availability capabilities including the elimination of single points of failure and scalability to at least eight physical nodes are required for production. Live migration, the ability to move running virtual machines (VM) from one host to another, is required. Other required features include support of hardware-assisted memory virtualization; support for iSCSI and Fibre Channel networked storage; security features including role-based access controls and auditing of administrative actions; and hypervisor licensing based on each physical server instance.
Examples of preferred features include memory overcommit; centralized virtual switch management; an integrated firewall; centralized hypervisor patch management; and automated VM provisioning.
Examples of optional features include automated server shutdown and start-up to conserve power; integration with third-party high availability software; and integration with storage virtualization appliances.
In addition to meeting 100% of required features, VMware holds the lead by offering more than 80% of preferred and optional features.
Citrix, at 85% of required features, falls short mainly in the security realm. Security logging and auditing of administrative actions; directory services integration; and role-based access controls are all missing from XenServer 5.0. However, directory services and role-based access control are expected to be added in the 5.5 version, Wolf said. Citrix is close to being ready for enterprise workloads, Wolf said.
Citrix offers 50% of preferred features and 58% of optional ones.
Virtual Iron, which is being purchased by Oracle, checks in at 83% of required features. Missing elements include an enterprise-class support policy; hot-add (the ability to add storage to a virtual server while it's running); a fault-tolerant management server; and integration with third-party management tools. Virtual Iron provides 46% of preferred features and 36% of optional elements.
Microsoft's Hyper-V offers 78% of required features but is missing live migration; hot-add; fault-tolerant management; hardware-assisted memory virtualization; and ability to provide a minimum of two virtual CPUs for each guest operating system. Microsoft also does not meet every high availability requirement detailed by the Burton Group. Microsoft has promised to add live migration to its hypervisor, but has not yet made the feature available.
Microsoft offers 43% of preferred features and 68% of optional ones.
These four hypervisors aren't the only ones on the market; Burton Group only recently devised its criteria and is evaluating them in order of market share and requests from clients. Wolf said other vendors to be evaluated in the future include Novell, Red Hat, Oracle and Parallels.
Although the guidelines seem pretty clear-cut, Wolf said each IT shop has to evaluate its own needs and choose a hypervisor accordingly. "Nothing is set in stone. You know your requirements better than anyone," Wolf's presentation stated. "Define your organization's virtualization requirements and stick to them."