==== How to Perform a Active/Standby Switch on NCSS Real-Time Systems ====

Read the section on [[getrole|determining]] the real-time system status for more information.
 
  - Log into either ucbrt or mnlort1 and examine the current eqassemble log file in /home/ncss/run/log/. Check the date of this file to see when it last changed. Then run "tail -f <eqassemble-log-file>" to see whether a new event is being assmbled. Only after you verify that no new events are in progress should you continue with the next step!
  - Log into mnlort1 and ucbrt (using ssh) as user //ncss//. This can be done by one or two people.
  - Run the command **set_role active** on the machine that is to become //Active//.
  - Run the command **set_role standby** on the machine that is to become //Standby//.
  - Check the status using the command **get_role**. This will report the current status of the machine as //Active// or //Standby//.
  - Proceed to the procedure for switching [[pp_howto:swap_pp|post-processing roles]].

The //set_role// command will send email and pager messages to report the change of status.

In the event that the machine which was //Active// crashes and is not available for login, you can proceed immediately to make the former //Standby// machine into //Active//. Whenever a real-time machine boots, it will set its status to //Standby// as part of the startup process. This will cause email and pager messages to be sent announcing that the booted machine is //Standby//.

After doing a Active-Standby switch of the real-time systems, it is important to switch the [[pp_howto:swap_pp|post-processing systems]] so they are running on the same side of the Bay as the Active real-time system, mentioned in the list above. Otherwise database replication problems are likely to happen.