KVM vs LXC containers
KVM vs LXC: isolation versus density
LXC containers share the host kernel and start in milliseconds with almost no overhead; KVM virtual machines boot their own kernel with 2–5% overhead and a genuine security boundary. For multi-tenant hosting the distinction is decisive: a kernel vulnerability in an LXC host is a vulnerability affecting every tenant on it.
| Dimension | KVM | LXC containers |
|---|---|---|
| Isolation boundary | Hardware-enforced | Kernel namespaces |
| Boot time | 5–15 seconds | Under a second |
| Overhead | 2–5% | Under 1% |
| Density | Lower | Much higher |
| Kernel choice | Yours | The host's |
| Multi-tenant safety | Strong | Depends entirely on the host kernel |
Which should you choose?
KVM
Choose KVM whenever the tenants do not trust each other — which includes every commercial hosting scenario.
LXC containers
LXC is excellent inside your own trust boundary, for example as containers on a KVM instance you already own.
Frequently asked questions
Is LXC less secure than KVM?
The isolation boundary is weaker by construction. A kernel escape in LXC reaches every container on the host; the equivalent in KVM requires a hypervisor escape, which is a substantially harder class of bug.
Can I run LXC inside a KVM VPS?
Yes, and it is a good pattern: hardware isolation from other customers, cheap container isolation for your own services.