Sources of information
You don't just need new technologies and tools—even if they are cool. Sometimes, a little help from a more experienced source can pull you out of a hole. In this regard, you are well covered, as the Hadoop community is extremely strong in many areas.
Source code
It's sometimes easy to overlook, but Hadoop and all the other Apache projects are after all fully open source. The actual source code is the ultimate source (pardon the pun) of information about how the system works. Becoming familiar with the source and tracing through some of the functionality can be hugely informative. Not to mention helpful when you are hitting unexpected behavior.
Mailing lists and forums
Almost all the projects and services listed in this chapter have their own mailing lists and/or forums; check out the home pages for the specific links. Most distributions also have their own forums and other mechanisms to share knowledge and get (non-commercial) help from the community...