If you need to shut down a Vertica node for maintenance, then ensure that you refer to the following steps to ensure that there is no loss in data:
Login to the Vertica database using the dbadmin user and run the following commands:
select close_all_sessions(); For more information, see the Vertica Documentation.
select make_ahm_now();
select do_tm_task('moveout');
select do_tm_task('mergeout');
select make_ahm_now();
Stop the node using admintools command: admintools -t stop_node -s <HOSTS> where -s <HOSTS> is a comma separated list of hosts on which the Vertica process needs to be stopped.