Solaris did not go open source. Oracle killed open source Solaris long time ago. Google,Facebook and Amazon were big from the start and needed specific hardware and software combo for their use cases. Solaris used to host 99% of the internet then Linux took off and it was cheaper and just good enough. Oracle failed to catch up and lure developers and companies in. Basically what Oracle did was that it "refused" (meaning poor service and support even if you paid a lot) to work with non-fortune 500 companies. It's still being used in most of your banks,insurance companies and large corporations all around the world. Oracle considered itself better than others and failed miserably to deliver. Also a lot of really neat futures that got into Linux were built on top of the giants from Solaris communities. It's really a shame to lose all of this.