The "Shared Kernel" Trap: Understanding OpenVZ Limitations
If you have shopped for a Virtual Private Server (VPS) in Norway recently, you have likely seen the race to the bottom on price. Providers offering 512MB of RAM for ridiculously low prices are everywhere. But here is the cold, hard truth: not all RAM is created equal.
Most budget hosting providers today rely on OpenVZ, an operating system-level virtualization technology based on the Linux kernel. While OpenVZ is fantastic for density—allowing a host to pack hundreds of containers onto a single physical server—it comes with a massive trade-off that rarely makes it into the marketing brochures: the "Noisy Neighbor" effect.
How OpenVZ Actually Works (And Why It Hurts Performance)
Unlike Xen or VMware ESX, which emulate hardware or use a hypervisor to create distinct environments, OpenVZ containers share the exact same Linux kernel (usually 2.6.18 in RHEL/CentOS 5 environments) as the host node. This means there is no true isolation for disk I/O or CPU scheduling.
When your neighbor decides to compile a massive kernel or run a poorly optimized MySQL query, your load average spikes. Why? Because you are fighting for the same system calls.
The Sysadmin's Reality Check:
If you are on an OpenVZ node, run this command right now:cat /proc/user_beancountersLook at the last column,failcnt. If you see any number other than 0 next toprivvmpagesorkmemsize, your provider is actively denying your application memory requests, even if `top` says you have free RAM. This is the dark side of "Burst RAM."
The Xen Advantage: True Hardware Isolation
This is why serious infrastructure is shifting toward Xen PV (Paravirtualization) or the emerging KVM technology. With Xen, your RAM is reserved at the hypervisor level. It cannot be stolen by another user. If you buy 1GB of RAM on a Xen node, that memory is physically allocated to your domain (domU).
Comparison: OpenVZ vs. Xen
| Feature | OpenVZ | Xen / CoolVDS HVM |
|---|---|---|
| Kernel | Shared (2.6.18) | Isolated (Customizable) |
| Swap Memory | Fake (Burst RAM) | Real Dedicated Swap |
| Performance | Fast until overloaded | Consistent & Predictable |
| Kernel Modules | Restricted (No iptables modules usually) | Full Control |
Why Location and I/O Matter More Than CPU
Beyond virtualization type, disk I/O is the new bottleneck. Traditional SATA drives running at 7200 RPM simply cannot handle the random read/write patterns of 50 concurrent VPS instances. This is why we are aggressively rolling out Enterprise SSD (Solid State Drive) storage across our nodes. In our benchmarks, replacing SAS 15k drives with Intel X25-E SSDs reduced MySQL query latency by over 80%.
Furthermore, for Norwegian businesses, data sovereignty is becoming critical. Under the Personopplysningsloven (Personal Data Act), you are responsible for where your customer data lives. Hosting in the US exposes you to the Patriot Act. Hosting on CoolVDS servers in Oslo ensures your data stays under the jurisdiction of Datatilsynet and benefits from low-latency peering at NIX (Norwegian Internet Exchange).
The CoolVDS Standard
We do not believe in the "overselling" business model. When you deploy a server with us, we utilize enterprise-grade virtualization that guarantees your resources. Whether you are running a high-traffic Magento store or a complex Postfix mail cluster, you need to know that your CPU cycles are yours alone.
Stop fighting over scraps of RAM. Upgrade to a platform designed for stability.
Need consistent I/O for your database? Deploy a high-performance Xen VPS with SSD storage on CoolVDS today.