We continue to see more evidence of the themes we discuss in our latest CAOS special report, Seeding the Clouds, which examines the open source software used in cloud computing, the vendors backing open source, the cloud providers using it and the impact on the industry.

First, as usual, we are seeing consistencies between our own research — which indicates open source is a huge part of today’s cloud computing offerings from major providers like Amazon, Google, Rackspace, Terremark and VMware — and that of code analysis and management vendor Black Duck. In its analysis of code that runs the cloud, Black Duck also found a preponderance of open source pieces, in many cases the same projects we profile in our report.

Indeed, open source software is an important part of the infrastructure, data and application layers of today’s cloud computing stacks with significant use of Linux, open source hypervisors KVM and Xen, open source data technologies such as MySQL, PostgreSQL, Hadoop, NoSQL and memcached and open source languages such as Java, PHP, Python and Ruby on Rails.

There will be plenty of users and customers content to use non-open source options that serve as the defacto standards, but we do see a move to higher-level, production and mission critical use, which represents continued commercial opportunity for open source and other vendors.

One of the more subtle effects of all this open source in the cloud, as covered in Seeding the Clouds, is the impact on discussions, debates and downright fights in the market. There is much scrutiny on claims of being open, technical aspects of open and what ‘open cloud’ means. A prime example is the Twisticuffs that have gone on between Simon Crosby of XenSource and Citrix, discussing OpenCloud and the response from Open Cloud Initiative co-founder Sam Johnston, who claims this is misuse of the open label.

We already saw open source playing a role in the discussions and debates about open clouds, open APIs and open data, and this latest confrontation is evidence that role continues to be significant. We still wonder though about the question of open enough as we contemplate openness in the clouds.