Hi! a few weeks ago I had the same question... Tried a first iteration at documenting this by going through the classes starting with key/value pairs in the blog post below.
Note it's not perfect yet but I think it should provide some insight into things. The lynch pin of it all is the DFSOutputStream and the DataStreamer classes. Anyways... Feel free to borrow the contents and roll your own , or comment on it & leave some feedback,or let me know if anything is missing.
Definetly would be awesome to have a rock solid view of the full write path.
On May 27, 2013, at 2:10 PM, Mahmood Naderan <[EMAIL PROTECTED]> wrote:
> I am trying to understand the source of of hadoop especially the HDFS. I want to know where should I look exactly in the source code about how HDFS distributes the data. Also how the map reduce engine tries to read the data.
> Any hint regarding the location of those in the source code is appreciated.