It is possible to adopt a structure for a plug connector coupling section having only one layer of contacts, by a structure where one side wall of a coupling section for coupling with a plug connector forms an insulator flange section 2b, while the other side wall thereof forms a first shell 4, contacts 3 being positioned in contact receiving grooves 2d provided in the flange section. In one example, output data generated by execution of a service on a primary server during a current epoch between a first checkpoint and a second checkpoint is buffered. The housing in the waist area encloses the person. The operational units can exchange data via the data inputoutput in normal mode and are not capable of exchanging data in the stall mode.