It's been a long time coming. Some of my customers are seeing growth rates that will soon outpace the ability to do any more vertical scaling of their websites. My own site was feeling the strain of several hundred thousand websites receiving XML update files daily. It was long past time to provide a solution for my customers (and my own sites) that could scale with the expected growth.
This weekend, I turned the keys on a new cluster hosting RicheyWeb.com. This development allows horizontal scaling as my traffic increases. When I reach a level of utilization that means customers and visitors see degraded performance - I can simply add another worker node to the cluster and increase the site capacity.
For my customers, it means that the Joomla sites they've been building upon for years will remain viable for years to come. This type of scaling allows for gradual growth, and even immediate / rapid expansion.