VPS hosting explained
A VPS is a slice of a physical machine that behaves like a machine of its own: your own operating system, your own root account, your own network interface. It is the first tier where you can install anything — and the first where patching is your problem.
- You get
- Root on a full OS, a public IP, and whatever you choose to run on it
- Virtualisation
- KVM gives you a real kernel; OpenVZ/LXC share the host's
- You are responsible for
- Updates, firewall, TLS, backups, monitoring — unless the plan says managed
- Scaling
- Resize the instance, or run several and put a load balancer in front
What "virtual private server" means literally
A hypervisor on a physical host carves its CPU, memory and disk into independent virtual machines. Each one boots its own operating system and sees its own virtual hardware. You get root inside yours and no visibility into the others.
Compared with shared hosting the change is categorical rather than incremental. You are no longer a user inside somebody's web server; you are an administrator of a server. Nothing is installed that you did not install, including the web server itself.
KVM versus container VPS — the one spec that matters
Two different things are sold as a VPS, and the difference is worth more than a gigabyte of RAM either way.
| KVM (full virtualisation) | OpenVZ / LXC (containers) | |
|---|---|---|
| Kernel | Your own — you can load modules, run any distro | Shared with the host — fixed kernel |
| Memory | Genuinely allocated to you | Often burstable and oversubscribed |
| Swap | Yours to configure | Frequently unavailable |
| Can run | Docker, custom kernels, WireGuard, NFS, anything | Restricted; some workloads simply refuse |
| Density | Lower, so it costs more | Higher, so it is cheaper |
Oversubscription, and why identical specs perform differently
Providers sell more virtual CPU than they physically own, on the reasonable assumption that not every tenant peaks at once. The ratio is never published. It is the single biggest reason two "2 vCPU / 4 GB" plans at the same price can differ by several times in real throughput.
Things that correlate with a fair ratio: dedicated-core plans, published CPU-use policies, NVMe rather than unspecified SSD, and a provider that lets you cancel monthly. Things that do not correlate with anything: the number of gigabytes in the plan name.
Benchmark before you migrate, not after. An hour of load testing on a fresh instance costs almost nothing and is the only honest measurement.
What you are signing up to run
Root is the product and also the bill. On an unmanaged VPS, every one of these becomes yours:
- Security updates. Unattended upgrades for the base system, and a plan for the things that need a restart.
- The firewall. Default-deny inbound, open only what you serve. Everything exposed will be scanned within hours.
- SSH hardening. Keys only, no password auth. Expect continuous brute force against port 22 from the first day.
- TLS. Certificates, renewal, and verifying that renewal actually works before it matters.
- Backups you have restored from. A snapshot you have never tested is a belief, not a backup.
- Monitoring. Disk filling up is the most common self-inflicted VPS outage, and it is entirely predictable.
Managed VPS plans take some of this back for a monthly fee. Read exactly where the line falls: "managed" sometimes means the full stack, and sometimes means they will reinstall the OS if you break it.
Snapshots, resizing and the reboot you did not expect
Most VPS platforms can snapshot a running instance and restore it to a new one. That makes a VPS far more forgiving than its reputation: take a snapshot before any upgrade and a failed change costs minutes.
Resizing is usually vertical and usually requires a reboot. Disk growth is often one-way — you can enlarge but not shrink — so oversizing the disk early is a decision you keep paying for.
When a VPS is the right answer
When you need to install something, when you want isolation from other customers, when you are running an application rather than a website, or when you have outgrown a shared plan's process limits. It is also the cheapest way to host many small sites on one bill, because nothing stops you putting thirty virtual hosts on one instance.
It is the wrong answer if nobody on the project wants to be an administrator. An unpatched VPS is strictly worse than shared hosting.