moodle/lang/en/help/directorypaths.html

<p align="center"><b>Directory paths</b></p>

<p>The full syntax of a directory path depends on your operating system:</p>

<blockquote>

<p>In <b>Windows Systems</b> use something like:
<ul> 
<li>c:\program files\data\moodle</li>
<li>c:\documents and settings\moodle\temp\saved</li>
</ul>
</p>

<p>In <b>Unix Systems</b> use something like:
<ul>
<li>/usr/data/moodle</li>
<li>/home/moodle/tmp/saved</li>
</ul>
</p>

</blockquote>

<p>Note that it's usually a good idea to make sure the directory already exists.  
   Sometimes Moodle can create the directory when required but this is not always possible.</p>

<p>Finally, make sure the case is correct (upper vs lower) and never include a trailing slash.</p>