title: IOError: No space left on device - which device?
body: <p>I'm uploading a small file (8.5 Mb) to a flask test server.</p>
  
  <p>When the file finishes uploading, the server reports:</p>
  
  <pre><code>    File "/home/ubuntu/.virtualenvs/eco_app/lib/python2.7/site-packages/wtforms/form.py", 
          line 212, in __call__
      return type.__call__(cls, *args, **kwargs)
      File "/home/ubuntu/.virtualenvs/eco_app/lib/python2.7/site-packages/flask_wtf/form.py", line 49, in __init__
          formdata = request.form
      File "/home/ubuntu/.virtualenvs/eco_app/lib/python2.7/site-packages/werkzeug/local.py", 
          line 338, in __getattr__
      return getattr(self._get_current_object(), name)
      File "/home/ubuntu/.virtualenvs/eco_app/lib/python2.7/site-packages/werkzeug/utils.py", 
           line 71, in __get__
      value = self.func(obj)
      File "/home/ubuntu/.virtualenvs/eco_app/lib/python2.7/site-packages/werkzeug/wrappers.py", 
           line 484, in form
      self._load_form_data()
      File "/home/ubuntu/.virtualenvs/eco_app/lib/python2.7/site-packages/flask/wrappers.py", 
          line 165, in _load_form_data
      RequestBase._load_form_data(self)
      File "/home/ubuntu/.virtualenvs/eco_app/lib/python2.7/site-packages/werkzeug/wrappers.py", 
          line 356, in _load_form_data
      mimetype, content_length, options)
      File "/home/ubuntu/.virtualenvs/eco_app/lib/python2.7/site-packages/werkzeug/formparser.py", 
          line 193, in parse
      content_length, options)
      File "/home/ubuntu/.virtualenvs/eco_app/lib/python2.7/site-packages/werkzeug/formparser.py",
          line 99, in wrapper
      return f(self, stream, *args, **kwargs)
      File "/home/ubuntu/.virtualenvs/eco_app/lib/python2.7/site-packages/werkzeug/formparser.py",
          line 210, in _parse_multipart
      form, files = parser.parse(stream, boundary, content_length)
      File "/home/ubuntu/.virtualenvs/eco_app/lib/python2.7/site-packages/werkzeug/formparser.py", 
          line 520, in parse
      return self.cls(form), self.cls(files)
      File "/home/ubuntu/.virtualenvs/eco_app/lib/python2.7/site-packages/werkzeug/datastructures.py", 
          line 373, in __init__
      for key, value in mapping or ():
      File "/home/ubuntu/.virtualenvs/eco_app/lib/python2.7/site-packages/werkzeug/formparser.py", 
          line 518, in &lt;genexpr&gt;
      form = (p[1] for p in formstream if p[0] == 'form')
      File "/home/ubuntu/.virtualenvs/eco_app/lib/python2.7/site-packages/werkzeug/formparser.py", 
          line 494, in parse_parts
          _write(ell)
  IOError: [Errno 28] No space left on device
  </code></pre>
  
  <p>Now, the server has plenty of free space - over 3Gb.</p>
  
  <p>I've looked at the <a href="https://github.com/mitsuhiko/werkzeug/blob/master/werkzeug/formparser.py" rel="noreferrer">Werkzeug github repo</a> to try to find the location that Werkzeug is trying to write to, but can't track it down.</p>
  
  <p>I've also checked <a href="http://flask.pocoo.org/docs/0.10/patterns/fileuploads/" rel="noreferrer">tempfile.gettempdir()</a> which gives /var/tmp as the temporary file directory, but this folder is practically empty, so I don't think that's the location that's creating the issue.</p>
  
  <p><strong>How do I find the device that has no space?</strong></p>