Genders and PDSH
Genders and PDSH grant a way to control multiple nodes at once. As such it will not function on a single node environment. To test its functionality:
Show a space separated list of all the nodes with the gender
nodeattr -s <gender>
Execute the uptime command on all nodes of the gender
pdsh -g <gender> uptime
This should show the time since last boot for each node.
All information about Genders and PDSH can be found the dedicated documentation section.