Container Orchestration vs. KVM Isolation: A Survival Guide for 2013

Let’s be honest: The last few weeks have been a wake-up call for anyone managing infrastructure in Europe. Between the PRISM leaks in June and the absolute explosion of "container hype" coming out of Silicon Valley with this new Docker project (currently in v0.5), the landscape is shifting under our feet.

I’ve spent the last decade in terminals, watching servers melt under load. I remember when "orchestration" meant a Bash script and a prayer. Today, we have better tools, but more confusion. If you are running a high-traffic shop in Norway—targeting users in Oslo or Bergen—you have a critical architectural decision to make right now.

Do you jump on the lightweight container bandwagon (LXC/OpenVZ) for density? Or do you stick to the iron-clad isolation of KVM? This isn't just about CPU cycles; it's about data sovereignty, neighbor noise, and whether you get woken up at 3 AM by a kernel panic.

The "Container" Trap: OpenVZ and the Lie of Resources

Most budget VPS providers in the Nordic market love OpenVZ. Why? Because they can cram 500 customers onto a single physical node, overselling RAM by 200%. They call it "burstable resources." I call it a ticking time bomb.

In OpenVZ, you share the kernel. If one client triggers a kernel panic, the whole node goes down. If one client gets DDoS'd, your I/O wait spikes. You can spot a choked OpenVZ container by checking the beancounters file. If you see the failcnt rising, your provider is throttling you.

cat /proc/user_beancounters 
# Look at the 'failcnt' column. 
# If it's > 0, you are hitting hard limits set by your host.

       uid  resource           held    maxheld    barrier      limit    failcnt
      101:  kmemsize        2641778    2920448   11055923   11377049          0
            lockedpages           0          0        256        256          0
            privvmpages       69652      74264      65024      69632      142

That 142 in failcnt? That’s 142 times your application crashed or stalled because the host said "no," even if top showed free RAM. For a serious Magento store or a MySQL cluster, this is unacceptable.

The New Contender: LXC and the Docker Experiment

LXC (Linux Containers) is the cleaner, mainline-kernel evolution of this concept. It’s what this new tool Docker is wrapping around. I’ve been testing Docker 0.4 on Ubuntu 12.04 LTS, and while the idea of packaging dependencies is brilliant, the orchestration is still manual.

To run LXC effectively in production today, you need to get your hands dirty with cgroups. You aren't just "running a container"; you are manually carving out resource slices.

# /var/lib/lxc/web01/config
# Limiting memory to 512MB to prevent OOM killer on the host
lxc.cgroup.memory.limit_in_bytes = 512M
lxc.cgroup.memory.memsw.limit_in_bytes = 1G
lxc.cgroup.cpu.shares = 1024

# Network isolation
lxc.network.type = veth
lxc.network.flags = up
lxc.network.link = br0

The performance is near-native, which is great for raw compute. But the security model is still maturing. If you are handling sensitive Norwegian user data—especially with the Datatilsynet watching—shared kernels are a risk factor. A root exploit in a container could theoretically escape to the host.

The Grown-Up Solution: KVM + Puppet

This brings us to the architecture I trust for critical workloads: KVM (Kernel-based Virtual Machine) orchestrated by Puppet. KVM provides full hardware virtualization. You get your own kernel. You can load your own modules (like ip_gre or specific TCP congestion controls) without begging support.

Pro Tip: In a KVM environment, use the deadline or noop I/O scheduler inside your VM if the host uses an intelligent RAID controller or SSDs. The default cfq creates double-queueing overhead.

With KVM, we don't just clone containers; we orchestrate infrastructure. Here is a snippet of a Puppet manifest we use to standardize our Nginx nodes across CoolVDS instances. This ensures that whether we deploy 1 server or 50, the configuration is identical.

# /etc/puppet/manifests/nodes/web.pp
node 'web-node-01' {
    package { 'nginx':
        ensure => installed,
    }

    service { 'nginx':
        ensure  => running,
        enable  => true,
        require => Package['nginx'],
    }

    file { '/etc/nginx/nginx.conf':
        ensure  => present,
        owner   => 'root',
        group   => 'root',
        mode    => '0644',
        source  => 'puppet:///modules/nginx/nginx.conf',
        notify  => Service['nginx'],
    }
    
    # Tune sysctl for high-concurrency
    sysctl { 'net.ipv4.tcp_tw_reuse': value => '1' }
}

Performance: The SSD Factor

Orchestration is useless if the disk is slow. In 2013, running a database on spinning rust (HDD) is negligent. We are seeing a massive shift toward SSDs.

At CoolVDS, we made a strategic choice to bypass the standard SATA SSDs for our high-performance tier and are testing early enterprise-grade storage solutions that reduce latency to practically zero. When your MySQL innodb_buffer_pool is backed by fast storage, KVM overhead becomes negligible compared to the stability gains.

Benchmark Comparison (Sysbench FileIO)

Final Verdict for the Norwegian Architect

If you are building a dev environment or a non-critical dashboard, play around with LXC or that new Docker tool. It’s fun, and it’s likely the future.

But if you are deploying a production banking app, an eCommerce store, or handling personal data under Norwegian law, isolation is not optional. You need KVM.

You need a system where your CPU credits are guaranteed, and your I/O isn't stolen by another customer's backup script. That is the philosophy we built CoolVDS on. We don't oversell, and we don't hide failcnt errors from you.

Ready to stop fighting for resources? Spin up a KVM instance on our high-performance SSD infrastructure. We offer direct peering at NIX for the lowest possible latency in the Nordics.