What is OpenStack?

Chris Kemp speaking recently:

“Openstack is not a product, it is a collection of projects designed to be productised,” he said. The companies making that effort today, he said, are focusing on large-scale opportunities.

“Customer participation drives the change that customers want,” he said, and with not many users deploying OpenStack to date there’s therefore not much impetus for change or innovation.

What is OpenStack?