Stop Playing Russian Roulette with Shared Kernels
If I see one more hosting provider selling "Burst RAM" as a feature, I might just pull the plug on the rack myself. It's 2010, and we need to stop pretending that container-based virtualization like OpenVZ is sufficient for high-load production environments. Sure, it's efficient, but when your neighbor's PHP script goes rogue, your database goes down. That is not a strategy; that is gambling.
At CoolVDS, we have seen enough kernel panics to know that true isolation isn't optional. That is why we architect our platform around Xen. Unlike the "software wrappers" used by budget hosts, Xen provides a hypervisor layer that strictly allocates CPU cycles and memory pages. If you are running a Magento store or a critical MySQL cluster targeting the Norwegian market, you cannot afford to fight for resources.
Paravirtualization (PV) vs. HVM: What You Need to Know
Many sysadmins are confused about the difference between Xen PV and HVM (Hardware Virtual Machine). In the Linux world, PV is currently king for performance.
With Paravirtualization, the guest OS (like your CentOS 5 or Debian Lenny instance) knows it is virtualized. It makes hypercalls directly to the hardware layer rather than emulating device drivers. This reduces overhead significantly.
Pro Tip: Always check your kernel. If you are running CentOS, ensure you are using the kernel-xen package. A standard kernel in a PV environment will fail to boot or perform miserably.The "Steal Time" Metric
How do you know if your host is overselling CPUs? The answer lies in top. Look at the %st (steal time) metric.
Cpu(s): 12.5%us, 3.2%sy, 0.0%ni, 82.1%id, 0.4%wa, 0.0%hi, 0.1%si, 1.7%stIf that last number climbs above 5-10%, your Virtual Private Server is waiting for the physical CPU to free up because other tenants are hogging it. On CoolVDS, we strictly cap and allocate CPU cores. We monitor our dom0 (the privileged domain) religiously to ensure your steal time stays at virtually zero. When you pay for a 2.4GHz core, you get a 2.4GHz core.
Storage I/O: The Bottleneck of 2010
CPU is fast. RAM is fast. Disks are... spinning. The biggest performance killer today is I/O wait time. While consumer SSDs are starting to appear, they aren't reliable enough for enterprise RAID arrays yet. We rely on 15k RPM SAS drives in RAID-10 configurations to ensure redundancy and speed.
However, configuration matters. When setting up your MySQL `my.cnf`, you must be aware of your file system barriers.
[mysqld]
innodb_buffer_pool_size = 512M
innodb_flush_log_at_trx_commit = 2Setting flush to 2 provides a massive speed boost on virtualized storage, though with a slight risk during a total power failure—a risk we mitigate with redundant power feeds and battery-backed RAID controllers at our Oslo data center.
Data Sovereignty and The Personal Data Act
We are seeing stricter enforcement from Datatilsynet (The Norwegian Data Protection Authority) regarding where data lives. Under the Personal Data Act (Personopplysningsloven), hosting customer data outside the EEA can be a legal minefield. Latency isn't the only reason to host in Norway.
By keeping your physical bits in Oslo, you aren't just getting sub-10ms pings to your local users; you are complying with Norwegian privacy standards. No vague "cloud" locations. You know exactly which rack your data sits in.
Deployment: The CoolVDS Way
We don't believe in clicking through slow web wizards. Stability requires predictability. Here is how a typical Xen config looks on our backend:
name = "client_vm_01"
memory = 1024
vcpus = 2
vif = [ 'bridge=xenbr0' ]
disk = [ 'phy:/dev/volgroup/client_vm_01,xvda,w' ]
bootloader = "/usr/bin/pygrub"Simple. Auditable. Robust.
Don't let your infrastructure be the reason you lose sleep. If you need low latency connectivity to NIX (Norwegian Internet Exchange) and resources that are actually guaranteed, it is time to upgrade.
Stop guessing. Start measuring. Deploy a Xen instance on CoolVDS today and see the difference in `htop` for yourself.