To set up the mirror for the first time, set the variable database_mode to ``mirror'' in snodb.config. Run snodb.perl -dir and snodb.perl -names to create the directory structure and hepdb.names file used by the mirror. Then, copy the existing database files over from the official database directory to to the mirror database directory, typically the same pathname as the official database files but with ``dbsm'' replacing ``dbs'' (this is set in snodb.config).
Start the mirror database server by issuing the command snodb.perl -server. Unlike with the slave nodes, which should normally run snodb.perl -process_updates, which starts and then stops the server, the mirror node should have the server running continuously.
Set database_mode back to ``official'' in snodb.config.
Finally, run snodb.perl -mirror to start the process which monitors the new todo_site and queue_site directories for updates and handles them appropriately.