OpenVZ Virtualization: The Good, The Bad, and The privvmpages

It starts with a simple yum update. Suddenly, your terminal freezes. You check free -m and see plenty of RAM, yet your Apache error logs are screaming "Cannot allocate memory." Welcome to the world of OpenVZ limits.

In the current landscape of 2009, virtualization is splitting into two distinct camps: the hardware emulation crowd (Xen, VMware) and the containerization crowd (OpenVZ, Virtuozzo). For many SysAdmins in Oslo and across Europe, the choice often comes down to budget versus control. But if you don't understand what's happening inside /proc/user_beancounters, you are flying blind.

The Architecture: A Chroot on Steroids

Unlike Xen, which uses a hypervisor to emulate hardware for a guest OS, OpenVZ uses a single patched Linux kernel (usually RHEL/CentOS based) to create isolated instances called containers or VEs (Virtual Environments). There is no hardware emulation overhead. The disk I/O you get is essentially native.

This architecture is brilliant for efficiency. We can pack more density onto a server, which drives down the cost of a VPS Norway based solution significantly. However, it introduces the "Shared Kernel" problem. If a user in VE 101 triggers a kernel panic, the entire physical node goes down. Everyone sinks with the ship.

The Pros: Speed and Scalability

• Near-Native Performance: Without the instruction translation overhead of a hypervisor, CPU and RAM performance are practically identical to bare metal.
• Instant Provisioning: Creating a new instance is just untarring a template. You can be online in seconds.
• Burstable Resources: This is the double-edged sword. OpenVZ allows you to use extra CPU cycles if the node is idle.

The Cons: The "Noisy Neighbor" & Memory Management

The biggest pain point with generic OpenVZ hosting is overselling. Providers pile 500 clients onto a single Quad-Core Xeon server, banking on the fact that not everyone will spike at once. When they do, your site crawls.

Furthermore, memory management in OpenVZ is unique. You aren't just limited by RAM; you are limited by kernel objects. Have you ever tried to optimize a MySQL my.cnf on a budget VPS?

# Checking your fail counts
cat /proc/user_beancounters

# Look for the 'failcnt' column on these parameters:
# privvmpages: Memory allocation limit
# numtcpsock: Limit on TCP sockets
# kmemsize: Kernel memory size

If you see the failcnt incrementing for numtcpsock, your high-traffic Nginx proxy will start dropping connections, even if you have 512MB of RAM "free." This is why understanding these parameters is critical for any serious deployment.

Storage Wars: Why 15k SAS Matters

In 2009, CPU is rarely the bottleneck for web hosting; Disk I/O is. With OpenVZ, because the file system is shared, a neighbor running a heavy backup script or a find / command can saturate the disk controller.

This is where hardware selection becomes paramount. At CoolVDS, we don't rely on standard SATA drives for our primary nodes. We utilize RAID-10 SAS 15k RPM arrays. The difference in random read/write performance is night and day compared to standard 7.2k drives. If you are running a database-heavy application like Magento or a busy vBulletin forum, standard SATA simply cannot keep up with the I/O wait times.

Pro Tip: If you are hosting critical data in Norway, remember the Personopplysningsloven (Personal Data Act). Ensure your host has physical presence and strict access controls in their Oslo or Stavanger datacenters. Latency to NIX (Norwegian Internet Exchange) should be under 5ms.

When to Choose OpenVZ (and CoolVDS)

OpenVZ is not the enemy. It is a tool. It is perfect for:

At CoolVDS, we configure our managed hosting plans with generous UBC (User Beancounter) limits. We don't want you hitting a wall just because you opened a few extra Apache threads. We monitor the physical nodes 24/7 to ensure no single user monopolizes the I/O, maintaining stability for everyone.

Final Verdict

If you need absolute kernel customization (loading your own modules for iptables or VPNs), you might need Xen. But for 90% of web workloads—LAMP stacks, mail servers, and proxies—OpenVZ offers unbeatable performance per krone.

Don't let a bad experience with an oversold provider ruin your perception of container technology. Experience the difference of properly tuned, enterprise-grade OpenVZ.

Is your current host dropping packets? Deploy a high-performance, RAID-10 backed instance on CoolVDS today and check your failcnt for yourself.