How do you create "Aliases" in Apache Tomcat?

I am working on a web application that allows users to upload attachments. These attachments are stored on a different drive than that of the web application. How can I create an alias (equivalent to Apache HTTP server's aliases) to this drive so that users can download these attachments?

Currently I am creating a context file and dumping it in CATALINA_HOME/conf/Catalina/localhost, but it gets randomly deleted every so often. The context file is named attachments.xml and the contents are shown below. I have also read about virtual hosts, but if I understand correctly, then a virtual host is not what I am looking for. I am using version 6.0.18 of Apache Tomcat.

attachments.xml:

<?xml version="1.0" encoding="UTF-8"?>
<Context docBase    = "e:\uploads\attachments"
     reloadable = "true"
     crossContext   = "true">
</Context>

Solution

I spent a lot more time researching this and found a solution that solves the random deletion of the context files. I found this excerpt on Apache's website under the host configuration section:

You can nest one or more Context elements inside this Host element, each representing a different web application associated with this virtual host.

The virtual hosts are stored in the server.xml file located at CATALINA_HOME\conf. Tomcat comes configured with localhost as the default host. So, if we add the contents of attachments.xml from the first post, we get the following:

<Host name="localhost"  appBase="webapps"
    unpackWARs="true" autoDeploy="true"
    xmlValidation="false" xmlNamespaceAware="false">

    <Context path="/attachments"
             docBase="e:\uploads\attachments"
             reloadable="true"
             crossContext="true" />
</Host>

This is as close as one can get to defining aliases similar to Apache's HTTP server, I think.