The Silent Killer: I/O Wait
Let’s be honest. Everyone is migrating to virtualized environments right now. It saves rack space, it reduces power consumption, and it makes provisioning a new CentOS 5 box instantaneous. But there is a dirty secret in the hosting industry that most providers won't tell you: Storage contention is killing your application speed.
I recently audited a client's setup running a high-traffic Magento store. They had plenty of RAM and four virtual CPUs, yet the site felt sluggish. A simple check with top showed the CPU wasn't working hard, but the load average was sky-high. The culprit? %wa (I/O wait).
$ iostat -x 2
Device: rrqm/s wrqm/s r/s w/s svctm %util
sda 0.00 12.00 0.50 45.00 18.00 95.00See that utilization? The disk system is choked. In a shared hosting environment or a cheap VPS, you are often fighting for disk heads on a SATA array with fifty other noisy neighbors. If one neighbor decides to run a backup script, your database latencies spike from 5ms to 500ms.
The SAN Fallacy vs. Local RAID 10
Many "Cloud" providers (a term getting thrown around too loosely these days) rely on massive SANs (Storage Area Networks) connected via Fibre Channel or iSCSI. While flexible, this adds network latency to every disk write. For a static website, fine. For a heavy transactional database like MySQL 5.1, it is a disaster waiting to happen.
This is why at CoolVDS, we took a pragmatic architectural stance. We avoid network storage for primary instances. We utilize local RAID 10 arrays with 15k RPM SAS drives. RAID 10 gives you the redundancy of mirroring with the striping speed of RAID 0. It’s expensive for us to implement, but the seek times are drastically lower than a congested SAN LUN.
Pro Tip: If you are stuck on a slow disk system, you can cheat latency by adjusting your MySQL configuration, though it comes with risk. Setting innodb_flush_log_at_trx_commit = 2 tells InnoDB to flush to the OS cache rather than the disk on every commit. You gain massive speed, but risk losing one second of data if the OS crashes. Weigh your risks.The SSD Revolution is Here (Finally)
We are just starting to see Enterprise SSDs (Solid State Drives) like the Intel X25 series become viable for servers. Yes, the cost per gigabyte is astronomical compared to spinning rust. However, for I/O heavy workloads, the math changes. An SSD can handle thousands of IOPS (Input/Output Operations Per Second) compared to maybe 150-180 IOPS for a 15k SAS drive.
If your dataset is small enough to fit on Flash storage, the performance jump isn't just incremental; it is a paradigm shift. Queries that took seconds became instantaneous. CoolVDS is currently rolling out limited slots for high-performance SSD VPS instances in our Oslo datacenter—specifically for clients who cannot tolerate seek latency.
Data Sovereignty: The Norwegian Advantage
Beyond raw speed, we need to talk about where your bits actually live. With the looming concerns regarding the US Patriot Act and the ongoing discussions around the Data Retention Directive here in Europe, location matters.
Hosting your data in Norway offers two distinct advantages:
- Legal Clarity: You are protected by the Norwegian Personal Data Act (Personopplysningsloven) and the oversight of Datatilsynet. Your data isn't sitting on a server in Virginia subject to foreign subpoenas.
- NIX Latency: If your customer base is in Scandinavia, physics is the law. Routing traffic through the Norwegian Internet Exchange (NIX) in Oslo ensures ping times as low as 2-5ms for local users. Routing that same traffic to a server in Frankfurt or London adds unnecessary hops.
Conclusion
Don't let your infrastructure be a black box. Demand to know what is running underneath your virtualization layer. Is it oversold SATA drives? Is it a choked SAN?
For serious workloads, you need dedicated spindles or the emerging speed of SSDs, running on a hypervisor like Xen that guarantees resource isolation. If you are tired of watching your %wa climb every time traffic spikes, it might be time to evaluate a provider that builds for performance first.
Need to benchmark? Deploy a CentOS instance on CoolVDS today and run your own I/O tests. The results will speak for themselves.