With the ever increasing demand of more and more internet traffic , one of the most important facets of any popular website is being able to handle that traffic and remain stable and fast. Downtime can be disastrous forcing customers and also revenue to look elsewhere.

What can be done? The solution is simple, redundancy, redundancy, redundancy. This can be achieved by using hardware and software to build out highly redundant and highly scalable network services. One of the most popular methods is currently load balancing your site across multiple machines.

Load balancing as defined in wikipedia is the following:

a technique to distribute workload evenly across two or more computers, network links, CPUs, hard drives, or other resources, in order to get optimal resource utilization, maximize throughput, minimize response time, and avoid overload. Using multiple components with load balancing, instead of a single component, may increase reliability through redundancy. The load balancing service is usually provided by a dedicated program or hardware device (such as a multilayer switch or a DNS server).

Now thanks to the Linux Virtual Server Project and the growth of Xen powered Virtual Servers provided by that great company dediserve.com , you can now very simply and very cheaply build out your own load balanced cluster for as little as €80 per month.

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We here in Dediserve are huge fans of Xen, after all our whole virtualized platform is built on it. However we did throughly investigate all the existing virtualization technologies currently on the market when we went to build out our own platform.

So to save you the same hassle i will outline below our feelings on each technology we looked at both good and bad.

Xen

Pro’s

• Using Paravirtualisation technology It allows several guest operating systems to be executed on the same computer hardware concurrently
• You can physically reboot the node with no affect to any other users on the same harrdware
• You can install and set-up Iptables
• You do not share resources and are guaranteed resources
• Its Free

Con’s

• Guanteed resources means having less users on each machine
• Not as mature as some of the other commercial virtualisation technologies

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