add 'common problems and solutions' section

index.html

@@ -331,6 +331,30 @@ <h2>Using EC2 for testing</h2>
 	might want a fast, dedicated server, or on Amazon EC2 large
 	(or better) instance.</p>
 
+        <h1>Common Problems and How to Solve Them</h1>
+
+        <h2>HDFS</h2>
+
+        <h3>Hadoop Filesystem Corruption: <code>InconsistentFSStateException</code></h2>
+        <p>
+          This might happen if you shut down all of of your Hadoop
+          namenodes and datanodes, and then try to bring them up again by doing:
+          <code>bin/hadoop namenode</code> and <code>bin/hadoop datanode</code>.
+        </p>
+
+        <p>
+          Here's a screenshot showing output from such a situation:
+        </p>
+
+        <a href="inconsistentfsstate.png"><img src="inconsistentfsstate.png"/></a>
+
+        <h4>Solution</h4>
+        <code>rm -rf /tmp/hadoop-$USER</code>
+
+        <h3>Hadoop Filesystem <code>'Incompatible build' errors at startup</code></h3>
+
+        <h4>Solution</h4>
+        <code>rm -rf /tmp/hadoop-$USER</code>
 
   </body>
 </html>