KVM vs. VMware: A Case Study

After a month of debate and experimentation, my employer has made the decision to use the open-source KVM virtualization infrastructure for migrating IT resources to a virtualized environment.  Below, I discuss why we chose KVM over its (mostly proprietary) alternatives.

Until a couple years ago, the open-source community offered no real contender in the virtualization market.  True, the qemu project has been around for a while, but qemu remains too inefficient for most production environments.  Xen has also existed since 2003, but for a long time it only supported a limited set of guest operating systems, which did not include Windows until late 2005.  As a result, proprietary virtualization products like VMware enjoyed a near-monopoly in the enterprise market until quite recently.

The rapid maturation of KVM, or ‘kernel-based virtual machine’, over the course of the last couple of years constituted the first open-source challenge to VMware.  Integrated into the Linux kernel, KVM provides feature-rich and highly efficient virtualization.

My colleagues and I tested KVM (running on an Ubuntu 8.04 host) and ‘barebones’ VMware ESX server over the last several weeks.  Ultimately, we decided KVM was a better fit for our needs based on the following considerations:

Perhaps the single major downside of KVM is that it requires a bit more technical know-how than VMware to deploy effectively, since some features can only be configured via manual hacking of XML files.  But as KVM and related tools continue to mature, expect that to change.

For IT staff interested in zero-cost, Linux-friendly, feature-rich and resource-efficient virtualization, KVM has become the way to go.  If VMware wants to compete, it needs to rise from the laurels of its crumbling monopoly by innovating and lowering costs.

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