If one of your NAM fronted applications is having issues, configure NAM to display a "Maintenance Page" rather than displaying the default NAM error page. This looks much more professional than a 504 Gateway Timeout page.
This works for NAM 3.1 SP2.
The maintenance page that will be displayed will be a .jsp file. In this example, we'll call it offline.jsp.
The first thing you need to do is create the NAM method and class:
The next thing you need to do is actually create the offline.jsp file on the IDP server(s).
-Create the offline.jsp file on all IDP servers in the /var/opt/novell/tomcat5/webapps/nidp/jsp/ directory. It can be as simple as a plain one line text file containing only "Down for Maintenance" or you can customize it if you are familiar with JSP's. Attached is a messy but working template you can use that allows you to at least have a custom header image.
Using the example above, the image.jpg file needs to be located in the /var/opt/novell/tomcat5/webapps/nidp/images/ directory on all IDP servers.
Note: If you make modifications to the offline.jsp file and you don't see the changes taking affect, delete offline_jsp.class and online_jsp.java files from the /var/opt/novell/tomcat5/work/Catalina/localhost/nidp/org/apache/jsp/jsp/ directory and try again.
Finally, you need to apply the "Maint Page" when needed: