Virtualization

I run VMs constantly. Testing Kubernetes deployments, trying out a distro I read about, running Windows for that one stubborn application, isolating an experiment so I don’t wreck my actual machine. KVM/QEMU is the right tool for all of it. Near-native performance, completely open source, baked straight into the Linux kernel. Nothing to phone home, nothing to license, no vendor deciding what I’m allowed to do with my own hardware. ...

Ask most people how to run a “real” hypervisor at home and you get the same shortlist: VMware, Hyper-V, or at minimum Proxmox. Something with a web UI, a clustering tab, a marketing page full of enterprise features. That mental model is so common that running virtual machines without one of those products feels like cutting corners. We’ve quietly accepted that serious virtualization comes with a vendor attached. Now flip it. The thing doing the actual work in all of those products is a Linux kernel module that has been production-grade for over a decade. KVM with libvirt gives you live migration, memory ballooning, CPU pinning, GPU passthrough, SR-IOV, nested virtualization. The features the glossy hypervisors advertise are kernel features. The web UI is a wrapper around them. ...

“So what’s the difference between a container and a virtual machine?” I get this question a lot, usually from someone smart who has been nodding along in meetings without quite wanting to admit they’re fuzzy on it. And the honest answer is that most explanations make things worse. They reach for “hypervisor,” “kernel sharing,” and “hardware abstraction” in the first sentence, and now the person has four new terms to be confused about instead of one. ...