The End of "Burst RAM": Why We Bet on KVM
If you have managed a Virtual Private Server (VPS) for more than a month, you know the feeling. It’s 3:00 AM, your Nagios pager goes off, and your MySQL replication has stalled. You SSH in, run top, and see your CPU usage is low, but your iowait is through the roof.
You aren't the problem. Your neighbor on the physical host is. They decided to recompile their kernel or run a massive backup script, and because you are likely on a legacy OpenVZ or Virtuozzo container, their load is your load.
At CoolVDS, we are done with the "shared kernel" limitations. With the maturation of the Linux 2.6.20+ kernel, KVM (Kernel-based Virtual Machine) has emerged as the only logical choice for system administrators who demand dedicated resources and true isolation.
The Architecture: Hypervisor vs. Container
To understand why we deployed KVM across our Oslo datacenter, you have to look at the kernel space.
OpenVZ (common in budget hosting) uses a single shared kernel. It relies on chroot on steroids. It is efficient, but it lies to you. The "Burst RAM" you see in your plan isn't real RAM; it's a probability calculation. If everyone claims it, the node crashes.
KVM turns the Linux kernel into a hypervisor. Each guest has its own kernel, its own memory space, and acts like a dedicated server. If your neighbor crashes their kernel, your uptime remains 100%. This is the stability mandated by serious SLAs.
Performance Benchmarking: The VirtIO Difference
Critics of KVM point to the overhead of full virtualization. In 2007, they were right. In late 2009, they are wrong. The introduction of VirtIO paravirtualized drivers has bridged the gap.
Instead of emulating a generic Realtek network card (which burns CPU cycles), VirtIO allows the guest OS to talk directly to the hypervisor.
Here is how we verify a proper KVM setup on a CentOS 5.4 guest. If you don't see these drivers loaded, you are losing 30-40% of your disk I/O throughput:
[root@coolvds-node ~]# lsmod | grep virtio
virtio_balloon 10816 0
virtio_net 14720 0
virtio_blk 13696 3
virtio_pci 12928 0
virtio_ring 10624 3 virtio_balloon,virtio_net,virtio_blk
Pro Tip: When installing your OS, always choose the VirtIO disk bus instead of IDE. In your Linux guest, this changes your drive mapping from/dev/hdato/dev/vda, significantly reducing CPU interrupt overhead during high write operations.
Storage: The 15k RPM SAS Advantage
Virtualization creates a "blender effect" on storage. Sequential writes from five different VMs become random writes on the physical disk. Standard SATA drives cannot handle this; the seek times will destroy your web server's response time (TTFB).
This is why CoolVDS utilizes Enterprise 15k RPM SAS drives in RAID-10. While solid-state drives (SSDs) like the Intel X25-M are promising, they are currently cost-prohibitive for mass storage. High-speed SAS arrays offer the reliability and IOPS needed for database-heavy applications right now.
The Norwegian Context: Latency and Law
Hosting physically in Norway isn't just about patriotism; it's about physics and legality.
1. Latency to NIX (Norwegian Internet Exchange)
If your target audience is in Oslo, Bergen, or Trondheim, routing traffic through a datacenter in Germany adds 20-30ms of unnecessary latency. By peering directly at NIX in Oslo, our KVM instances achieve sub-3ms ping times to major Norwegian ISPs like Telenor and NextGenTel.
2. Compliance (Personopplysningsloven)
Data privacy is becoming a headache for CTOs. Under the Personopplysningsloven (Personal Data Act of 2000) and the oversight of Datatilsynet, storing sensitive customer data outside the EEA can be a legal minefield. Hosting locally simplifies compliance. You know exactly where your hard drives are spinning.
Configuration: Optimizing Your KVM Instance
Once you spin up a CoolVDS instance, don't leave it at default settings. Here is a quick win for your filesystem to reduce write operations on the physical disk:
Edit your /etc/fstab to include the noatime flag. By default, Linux writes a timestamp every time you read a file. On a busy web server, this is useless I/O.
LABEL=/ / ext3 defaults,noatime 1 1
tmpfs /dev/shm tmpfs defaults 0 0
Conclusion
The era of oversold, unstable container hosting is ending for professional deployments. If you need to run custom kernel modules, require strict resource guarantees, or simply want to avoid the "noisy neighbor" effect, KVM is the industry standard we are backing.
Don't let I/O wait kill your project. SSH into a true hardware-virtualized environment.
Ready to compile your own kernel? Deploy a CentOS or Debian KVM instance on CoolVDS today.