iFastHostingWhat is KVM virtualisation?
KVM gives every VPS its own genuine virtual machine and kernel, isolated from every other guest on the same physical host.
KVM (Kernel-based Virtual Machine) is virtualisation technology built directly into the Linux kernel that turns a physical server into a hypervisor, able to run several independent, fully isolated virtual machines on it. Each one gets its own kernel, its own virtualised hardware, and behaves — from inside it — exactly like a standalone computer, rather than a process sharing an operating system with anything else on the host.
Why this matters for a VPS
Not every kind of "virtual server" works the same way underneath. Container-based virtualisation (such as OpenVZ, historically common on cheaper VPS platforms) has every guest share the same host kernel, with lighter isolation between them. KVM instead gives each guest a genuinely separate virtual machine, including its own kernel — the isolation is closer to running on separate physical hardware, and a guest can run a different kernel version or even swap kernels independently of what the host itself is running.
| KVM | Container-based virtualisation | |
|---|---|---|
| Kernel | Each guest has its own | Shared with the host |
| Isolation | Full virtual machine boundary | Lighter, kernel-level isolation |
| Kernel-level customisation | Available to the guest | Generally not available |
| Flexibility of OS choice | Broad — any OS the hypervisor supports | Constrained to what the host kernel supports |
What this means in practice
- You get a real, independent operating system instance, with root access to configure it at the kernel level if your workload genuinely needs that.
- Your VPS's resource allocation and isolation from other guests on the same host does not depend on kernel-level sharing tricks.
- A kernel panic or a low-level fault in one guest has no way to affect another guest on the same physical host, because they do not share a kernel to be affected through.
KVM is the virtualisation technology most modern VPS platforms are built on today, including ours — see /vps-hosting for current plans. If you are weighing up a VPS against other options entirely, what a VPS is and VPS or dedicated server: where the line is cover the broader decision that KVM is only one part of.
Related reading
A dedicated, isolated slice of a physical server that behaves like your own machine, with root access and nobody else sharing your resources.
VPS or dedicated server: where the line isA VPS is an isolated slice of shared hardware; a dedicated server is the entire physical machine to yourself. Here is what that changes.
How much RAM does my VPS need?It depends what is running, but free -h on an existing server and a look at what each extra service costs gets you a real answer fast.
How to add swap space to a VPSCreating a swap file with fallocate and mkswap, making it permanent in fstab, and why swap is a cushion rather than a substitute for RAM.