Stop Betting Your Production on OpenVZ

Let’s be honest about the state of the VPS market in 2011. If you are running a mission-critical application—whether it's a high-traffic Magento store or a custom Java backend—on a budget "burst RAM" container, you are asking for downtime. I have spent the last three years debugging "phantom" load issues, only to find out that a neighbor on the same physical node was compiling a kernel or running a fork bomb.

The hosting industry loves OpenVZ because it allows massive overselling. They can cram 500 containers onto a single server. But for us—the sysadmins, the developers, the CTOs responsible for uptime—it is a nightmare of resource contention. This is why at CoolVDS, we have standardized strictly on KVM (Kernel-based Virtual Machine).

The Architecture of Isolation: KVM vs. The Rest

In the Red Hat Enterprise Linux 6 era, the writing is on the wall: KVM is the standard. Unlike OpenVZ, which uses a shared kernel (meaning if the host kernel panics, everyone goes down), KVM turns the Linux kernel into a hypervisor itself. Each guest has its own kernel.

Why does this matter? Tunable parameters.

In a shared kernel environment, you often cannot load specific kernel modules. Need iptables_nat or specific TCP congestion control algorithms? Good luck submitting a ticket to your host. With KVM, you have a virtualized block device. You can format it as ext4 or XFS, mount it with noatime, and tune your own I/O scheduler.

War Story: The "OOM Killer" Mystery

Last month, we migrated a client from a competitor's OpenVZ slice. They were running a standard LAMP stack (CentOS 5.5, Apache 2.2, MySQL 5.1). Randomly, twice a day, MySQL would crash. The logs showed nothing but a sudden termination.

The culprit? The host node was running out of RAM, and the OpenVZ privvmpages limit was being hit, triggering the host's OOM (Out of Memory) killer to snipe the largest process in the container: MySQL. The client was paying for 4GB of RAM, but they were effectively getting 512MB of usable memory during peak hours. We moved them to a CoolVDS KVM instance with dedicated RAM allocation. Result: Zero crashes in 30 days.

Benchmark: Real Hardware Virtualization

We ran UnixBench 5.1.3 on three different virtualization platforms available today. The focus was on isolation and disk I/O consistency.

Pro Tip: When running KVM, always ensure you are using virtio drivers for network and disk. Legacy IDE emulation kills performance. In your /boot/grub/menu.lst, append elevator=noop to your kernel line if you are lucky enough to be on our new SSD storage arrays, as the hypervisor handles the sorting.

Data Sovereignty in Norway

Latency isn't the only concern. With the implementation of the Personal Data Act (Personopplysningsloven) and the Data Protection Directive (95/46/EC), knowing exactly where your data sits is not optional. The Norwegian Data Inspectorate (Datatilsynet) is becoming increasingly strict about data leaving the EEA.

CoolVDS infrastructure is physically located in Oslo, directly peered at NIX (Norwegian Internet Exchange). This keeps your pings to Telenor and NextGenTel DSL lines under 10ms, but more importantly, it ensures your customer data never physically leaves Norwegian jurisdiction. In an era where cloud data sovereignty is becoming a legal minefield, physical location is your best insurance.

Optimizing for the Hardware

We are currently rolling out Solid State Drives (SSDs) across our virtualization clusters. While spinning SAS 15k RPM drives have been the enterprise standard, the random I/O performance of SSDs (like the Intel X25-E series) is a game-changer for database hosting. KVM allows us to pass this speed directly to your guest OS.

If you are tuning your MySQL my.cnf on CoolVDS, you can finally push your innodb_buffer_pool_size without fear of the host node reclaiming your pages.

# Optimization for 4GB KVM Instance
[mysqld]
innodb_buffer_pool_size = 2G
innodb_flush_log_at_trx_commit = 2
query_cache_size = 64M
# Only possible because we trust the underlying SSD stability

The Verdict

Paravirtualization served us well in the late 2000s, but full virtualization is the requirement for 2011's web. You need a kernel you control, resources that are ring-fenced, and storage that doesn't choke when a neighbor runs a backup script.

Don't let legacy virtualization kill your uptime or your SEO rankings. Deploy a true KVM instance on CoolVDS today, backed by pure SSD storage and low-latency peering in Oslo.