Stop Letting "Noisy Neighbors" Kill Your Uptime
It’s 3:00 AM. Your monitoring system is screaming. Your Apache process is hanging, but load average inside the container says 0.2. You dig deeper, only to realize the physical host node is thrashing because another customer on the same box decided to run a massive backup script. If you are running on OpenVZ or Virtuozzo, this story is probably familiar.
In the world of VPS hosting, there is a dirty little secret: overselling. Container-based virtualization like OpenVZ shares the host's kernel. It’s efficient for the host, sure, but it means you are at the mercy of everyone else on that server. For a dev sandbox? Fine. For a production MySQL database serving customers in Oslo? Absolutely not.
At CoolVDS, we took a different path. We built our infrastructure on KVM (Kernel-based Virtual Machine). Here is why the battle-hardened systems administrators are migrating to KVM in 2010, and why you should too.
The KVM Architecture: True Isolation
Unlike containers, KVM turns the Linux kernel into a hypervisor (merged into mainline kernel 2.6.20). Each Guest VM has its own private virtualized hardware: its own network card, disk controller, graphics adapter, and most importantly, its own kernel.
This means if a neighbor kernel panics, you stay up. If a neighbor exhausts their segment of the slab cache, your memory remains yours. You get a raw block device, not just a directory on the host's filesystem.
The Performance Myth: "KVM is Slow"
A few years ago, full virtualization meant slow emulation (QEMU). That is no longer the case. With modern CPU extensions (Intel VT-x and AMD-V) and the maturity of virtio paravirtualized drivers, the overhead is negligible.
If you aren't using `virtio` drivers on your KVM instances, you are leaving performance on the table. Here is what a proper disk definition looks like in your libvirt XML config to bypass full emulation overhead:
<disk type='file' device='disk'>
<driver name='qemu' type='raw' cache='none'/>
<source file='/var/lib/libvirt/images/coolvds-guest.img'/>
<target dev='vda' bus='virtio'/>
</disk>
Pro Tip: Always set your disk cache policy tononeorwritebackwhen using KVM with raw partitions. This lets the guest OS manage its own filesystem cache without fighting the host's I/O scheduler.
Storage: Why Spindles Are the Bottleneck
CPU power is cheap. RAM is getting cheaper. But Disk I/O? That is where servers go to die. Most budget hosts use SATA drives in RAID 5. It looks like a lot of space, but the random write performance is abysmal.
We are seeing a massive shift right now towards Solid State Drives (SSDs). The random IOPS (Input/Output Operations Per Second) on an Intel X25-series SSD obliterates even the fastest 15k RPM SAS drives. While SSD storage is still a premium tier, for high-traffic databases, it is the only logical choice.
| Feature | OpenVZ / Containers | CoolVDS (KVM + SSD) |
|---|---|---|
| Kernel | Shared (Old 2.6.18 RHEL5) | Dedicated (Run latest 2.6.32!) |
| Isolation | Processes can be killed by host OOM | Full RAM allocation guaranteed |
| Swap | Fake "Burst" RAM | Real Partition Swap |
| Storage | Often SATA | Enterprise SSD / SAS RAID 10 |
Data Sovereignty in Norway
Latency isn't just about disk speed; it's about physics. If your customers are in Scandinavia, hosting in Texas is a mistake. You’re looking at 120ms+ latency. Hosting in Oslo reduces that to <10ms.
Furthermore, the Personal Data Act (Personopplysningsloven) and the Data Inspectorate (Datatilsynet) here in Norway set a high bar for privacy. By keeping your data on CoolVDS servers physically located in Oslo, you simplify compliance with local regulations and the EU Data Protection Directive. You know exactly where your bits live.
The Verdict
If you are running a static HTML site, buy a cheap shared plan. But if you are deploying a Java Tomcat cluster, a high-traffic Magento store, or a custom Rails app, you need the predictability of KVM.
Don't let legacy virtualization hold your infrastructure back. Experience the difference of dedicated kernels and SSD storage.
Ready to compile your own kernel? Deploy a high-performance KVM instance on CoolVDS today.