OpenVZ: The Double-Edged Sword of Virtualization

Let’s be honest. If you have been in the hosting game for more than a week, you have seen the dirt cheap VPS offers flooding the market. $5 for a slice of a server? It sounds great until your MySQL process gets killed by the host node because another user decided to compile a kernel on a Friday night.

I’ve managed racks from Oslo to Kyiv, and the debate between OpenVZ and Xen is usually settled by one thing: do you understand what you are actually buying? Today, we are stripping away the marketing fluff to look at the kernel-level reality of OpenVZ containers.

The Architecture: One Kernel to Rule Them All

Unlike Xen, which uses a hypervisor to present hardware to the guest OS, OpenVZ uses operating system-level virtualization. There is only one kernel running: the host's. Your "server" is essentially a chroot environment on steroids, wrapped in a container (VE).

The Good: Raw Speed.
Because there is no hypervisor translation layer and no duplicate kernel to load, the overhead is near zero. Disk I/O and CPU execution are native. In our benchmarks at CoolVDS, an OpenVZ container running Apache 2.2 on CentOS 5 boots in seconds, not minutes.

The Bad: The Noisy Neighbor.
Since you share the kernel, you share the fate of the node. If a neighbor triggers a kernel panic, the whole ship goes down. Furthermore, you cannot modify the kernel. Need to load a specific IPTables module or a TUN/TAP device for OpenVPN? If the host admin hasn't enabled it for you, you are out of luck.

The "Burst RAM" Myth

This is where most providers catch you. OpenVZ allows for "Burstable RAM." They sell you 256MB guaranteed, with 512MB burst. It looks good on paper.

But memory management in OpenVZ isn't handled like a standard Linux system. It relies on User Beancounters (UBC). If you exceed your limits, the kernel doesn't swap gently; it kills processes. Hard.

Pro Tip: Check Your Limits
Log into your VPS right now and run this command: cat /proc/user_beancounters
Look at the last column, failcnt. If you see any number other than 0 next to privvmpages or physpages, your provider is squeezing you, and your applications are silently failing.

OpenVZ vs. Xen: The 2009 Showdown

When to Use OpenVZ

Despite the criticism, OpenVZ is a powerhouse for the right workload. If you are running a standard LAMP stack (Linux, Apache, MySQL, PHP) and need maximum density and speed, it is unbeatable.

• Web Serving: Nginx 0.7 serving static files screams on OpenVZ.
• Development: Spawning 10 instances for a dev team takes seconds.
• DNS/Mail: Low resource usage services fit perfectly here.

However, the hardware matters. At CoolVDS, we don't put OpenVZ on standard SATA drives. We utilize enterprise SAS 15k RPM RAID-10 arrays. The high rotational speed and RAID striping mitigate the I/O contention that plagues cheaper hosts.

The Norwegian Context: Why Location Matters

Latency is the silent killer of user experience. If your customers are in Oslo, Bergen, or Trondheim, hosting in a datacenter in Texas is technical suicide. The round-trip time (RTT) alone will make your snappy AJAX interface feel sluggish.

Furthermore, we have the Personopplysningsloven (Personal Data Act) and the watchful eye of Datatilsynet. Keeping your data on Norwegian soil, within the NIX (Norwegian Internet Exchange) infrastructure, isn't just about speed—it's about legal peace of mind. You don't want to explain to your client why their customer data is sitting on a server subject to the US Patriot Act.

Final Verdict

Don't fear OpenVZ. Fear the configuration. A well-tuned OpenVZ container on a non-oversold node with fast SAS storage is often faster than a Xen VPS struggling with hypervisor overhead.

If you need raw performance for web hosting and want your data safe in Norway, we’ve tuned our User Beancounters so you never see a failcnt.

Stop guessing your resource limits. Deploy a high-performance OpenVZ instance on CoolVDS today and experience the stability of a properly managed container.