Open three terminals, and create three directories: %db1%, %db2% and %arb% Starting the daemons (2 data, 1 arbiter): mongod --dbpath=./db1 --port 13000 --replSet seta --smallfiles --logpath=db1.log mongod --dbpath=./db2 --port 13001 --replSet seta --smallfiles --logpath=db2.log mongod --dbpath=./arb --port 13002 --replSet seta --smallfiles --logpath=arb.log Configure the set: $ mongo localhost:13000 > rs.initiate( { _id: 'seta', members: [ { _id: 0, host: 'localhost:13000' } ] } ); seta:PRIMARY> rs.add('localhost:13001'); seta:PRIMARY> rs.addArb('localhost:13002'); Check whether it worked: seta:PRIMARY> db.isMaster(); seta:PRIMARY> rs.status();