Final answer:
The command to permanently decommission a Peer node varies by system; in Hadoop, it's often 'hdfs dfsadmin -refreshNodes' following exclusion list updates.
Step-by-step explanation:
The command used to permanently decommission a Peer node depends on the specific clustering or distributed system software you are using. Generally, such action is taken by the system administrator. For instance, in a Hadoop cluster, the command hdfs dfsadmin -refreshNodes is used following updates to the exclude list to decommission a node. In other environments, the commands may differ, and it is important to refer to the specific documentation for your environment or clustering solution. Decommissioning is a critical process to ensure data integrity and redistribution before a node is permanently removed from the cluster.