title: Input / Output error when using HDFS NFS Gateway
body: <p>Getting "Input / output error" when trying work with files in mounted HDFS NFS Gateway. This is despite having <a href="http://community.hortonworks.com/answers/82321/view.html" rel="nofollow noreferrer">set</a> <code>dfs.namenode.accesstime.precision=3600000</code> in Ambari. For example, doing something like...</p>
  
  <pre class="lang-sh prettyprint-override"><code>$ hdfs dfs -cat /hdfs/path/to/some/tsv/file | sed -e "s/$NULL_WITH_TAB/$TAB/g" | hadoop fs -put -f - /hdfs/path/to/some/tsv/file
  $ echo -e "Lines containing null (expect zero): $(grep -c "\tnull\t" /nfs/hdfs/path/to/some/tsv/file)"
  </code></pre>
  
  <p>when trying to remove nulls from a tsv then inspect for nulls in that tsv based on the NFS location throws the error, but I am seeing it in many other places (again, already have dfs.namenode.accesstime.precision=3600000). Anyone have any ideas why this may be happening or debugging suggestions? Can anyone explain what exactly "access time" is in this context?</p>