Both Solaris software and Sun 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, Sun Cluster might not be able to restart on that node. 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 Sun Cluster services, use this procedure to clear the full file system. Refer to Viewing System Messages in System Administration Guide: Advanced Administration for more information.