Deploy a Replica Set for Testing

mongoreplica

//start mongod instances
mongod --port 27017 --dbpath data/rs0-0 --replSet rs0 --smallfiles --oplogSize 128
mongod --port 27018 --dbpath data/rs0-1 --replSet rs0 --smallfiles --oplogSize 128
mongod --port 27019 --dbpath data/rs0-2 --replSet rs0 --smallfiles --oplogSize 128


//add primary
rsconf = {
           _id: "rs0",
           members: [
                      {
                       _id: 0,
                       host: "localhost:27017"
                      }
                    ]
         }

rs.initiate( rsconf )
rs.conf()

//add secondaries
rs.add("localhost:27018")
rs.add("localhost:27019")


//add some data
db.users.insert({name:"G"})
db.users.insert({name:"P"})
db.users.insert({name:"A"})
db.users.insert({name:"S"})

//do a query
db.users.find()

//to read from SECONDARY use
rs.slaveOk()

//set 0 priority
cfg = rs.conf()
cfg.members[2].priority = 0
rs.reconfig(cfg)