Note that changes in node config require a restart of slurmctld to take effect.

doc/man/man5/slurm.conf.5

@@ -1172,9 +1172,12 @@ the first task terminates before terminating all remaining tasks. The
 "\-\-wait" option on the srun command line overrides this value. 
 If set to 0, this feature is disabled.
 May not exceed 65533.
+
 .LP
 The configuration of nodes (or machines) to be managed by Slurm is 
 also specified in \fB/etc/slurm.conf\fR. 
+Changes in node configuration (e.g. adding nodes, changing their
+processor count, etc.) require restarting the slurmctld daemon.
 Only the NodeName must be supplied in the configuration file.
 All other node configuration information is optional.
 It is advisable to establish baseline node configurations,