Both Oracle Solaris software and Oracle Solaris Cluster software write error messages to the /var/adm/messages file, which over time can fill the /var file system. If a cluster node's /var file system fills up, Oracle Solaris Cluster might not be able to start on that node at the next boot up. Additionally, you might not be able to log in to the node.
If a node reports a full /var file system and continues to run Oracle Solaris Cluster services, use this procedure to clear the full file system. Refer to Removing Old or Inactive Files in Managing Devices in Oracle Solaris 11.4 for more information.