KVM: should it be ignored as a hypervisor alternative?

Virtualisation is often the first step towards cloud and the hypervisor is the starting point: is it time for KVM to be given a fair shake?

It has been a good couple of years for open source virtualisation product KVM. Available as part of Red Hat Enterprise Linux, SUSE Linux Enterprise and Canonical Ubuntu, KVM is now a serious competitor to established products such as VMware's vSphere,  Microsoft's Hyper-V and Citrix's Xen.

In 2011, the Open Virtualization Alliance  was formed by IBM, HP, Red Hat, BMC Software, Eucalyptus Systems, SUSE and Intel. Since then, it has gathered over 250 members many of whom are delivering solutions, such as management software, to make KVM a viable enterprise solution.

In terms of performance, KVM is no slouch. At the end of January 2013, it held the top 7 SPECVirt benchmarks. SPEC industry standard benchmarks are used by vendors to highlight the capabilities of their solutions and it is rare that an open source solution holds so many. Of more interest is that when put head to head with VMware, KVM outperforms it across 2,4 and 8 socket servers.

All of this sounds good and the list of end-users, especially large enterprise customers, is growing. Ask around at shows, however, and KVM is unlikely to be the first virtualisation product that many people mention. Talk to the very large cloud vendors and it is a different proposition. There are an increasing number of very large cloud providers who now offer KVM as an alternative to VMware and Microsoft. The interest is even higher when you look at the smaller cloud providers who have moved from being hosting companies to cloud providers.

There are an increasing number of very large cloud providers who now offer KVM as an alternative to VMware and Microsoft

The reason for this interest in KVM is twofold. The first is that a lot of these suppliers have an established history of delivering Linux. The second is cost because it is cheaper to deploy KVM than other virtualisation products. This wasn't always the case. Both Microsoft and VMware have increased the cost per virtual machine in recent years. KVM, as a newcomer, is therefore much cheaper.

If could be argued that this is never going to be a fair comparison because there are management suites and other products from the key virtualisation vendors that are tightly bound to their hypervisors. KVM, on the other hand, relies on a third party industry, OVA, to provide all of this and those products have to be licensed separately. However, if you just look at the cost per VM, there is a significant difference.