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<p>A distributed implementation of {@link
org.apache.hadoop.fs.FileSystem}.  This is loosely modelled after
Google's <a href="http://labs.google.com/papers/gfs.html">GFS</a>.</p>

<p>The most important difference is that unlike GFS, Hadoop DFS files 
have strictly one writer at any one time.  Bytes are always appended 
to the end of the writer's stream.  There is no notion of "record appends"
or "mutations" that are then checked or reordered.  Writers simply emit 
a byte stream.  That byte stream is guaranteed to be stored in the 
order written.</p>

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