To perform unplanned maintenance in the event of a failure

1. Check the database state.

   See Getting the Status of HADB

   • If the database state is Operational or better:

     The machines needing unplanned maintenance do not include mirror nodes. Follow the single machine procedure for each failed machine, one DRU at a time. HADB service is not interrupted.

   • If the database state is Non-Operational:

     The machines needing unplanned maintenance include mirror nodes. One such case is when the entire HADB is on a single failed machine. Get all the machines up and running first. Then clear HADB and recreate the session store. See Clearing a database. This interrupts HADB service.