NFS clients can maintain use of a file over a halt or reboot (although experiencing a failure to respond during that time), but CIFS clients cannot do so safely. Therefore, if the filer is running CIFS, the halt command invokes cifs terminate, which requires the -t option. If the filer has CIFS clients and you invoke halt without -t, it displays the number of CIFS users and the number of open CIFS files. Then it prompts you for the number of minutes to delay. cifs terminate automatically notifies all CIFS clients that a CIFS shut-down is scheduled in mins minutes, and asks them to close their open files. CIFS files that are still open at the time the filer halts will lose writes that had been cached but not written.
halt logs a message in /etc/messages to indicate that the system was halted on purpose.