As mentioned in the Software Configuration section, the Lemur Project-Cluster is running Apache HTTPD 2.2.2. Because of the potential for the load on the front-end server to become overwhelming, have instituted a load-balancing approach to providing web services on the cluster. When a request on port 80 (the standard httpd port) comes into the front-end, the Linux Virtual Server (LVS) software will automatically ship the request off to one of the back end nodes. The system tries to forward the request to the back-end node with the most amount of free CPU cycles on it at the given time.
The main htdocs directory can be found at /bos/usr0/htdocs, and is configured to be available from all of the back-end nodes as well. This means, when you create or modify a file in the htdocs directory (or subdirectory), it is instantly available to all of the web services on all of the nodes.
Because of the potential for each request to the cluster to be given to a different machine on the back-end, this may cause problems for session persistence. If you are working with PHP, the cluster is configured to share session information across all of the back-ends, so no modification is necessary for your code.
If you are not using PHP, and need to ensure session persistence, you can
try either of the following: