Awesome

Mongodb Tutorial

This tutorial only use one machine for demo purpose.

mongoid is used as ruby ODM framework of MongoDB.

Replica Set

Create database repositories

mkdir -p /usr/local/var/mongodb_replica1
mkdir -p /usr/local/var/mongodb_replica2
mkdir -p /usr/local/var/mongodb_replica3
ls -alh /usr/local/var/mongodb_replica*

Start servers

mongod run --config config/mongod.replica1.conf &
mongod run --config config/mongod.replica2.conf &
mongod run --config config/mongod.replica3.conf &
ps aux | grep mongod

Initiate relica set

mongo localhost:27021
> rs.help()
> config = {
  _id: 'demoReplicaSet',
  members: [
    { _id: 0, host: 'localhost:27021' },
    { _id: 1, host: 'localhost:27022' },
    { _id: 2, host: 'localhost:27023' } ]
  }
> rs.initiate(config)
> rs.status()

Open mongo consoles in different shells

mongo localhost:27021
mongo localhost:27022
mongo localhost:27023

Open web ui

open http://localhost:28021
open http://localhost:28022
open http://localhost:28023

Run demo scripts to populate data

bin/replica_set.rb

Failover

kill -9 [process_id of primary replica]

Master Slave

Create database repositories

mkdir -p /usr/local/var/mongodb_master
mkdir -p /usr/local/var/mongodb_slave1
mkdir -p /usr/local/var/mongodb_slave2
ls -alh /usr/local/var/mongodb_master /usr/local/var/mongodb_slave*

Start servers

mongod run --config config/mongod.master.conf &
mongod run --config config/mongod.slave1.conf &
mongod run --config config/mongod.slave2.conf &
ps aux | grep mongod

Open mongo consoles in different shells

mongo localhost:27018
mongo localhost:27019
mongo localhost:27020

Open web ui

open http://localhost:28018
open http://localhost:28019
open http://localhost:28020

Run demo scripts

bin/master_slave.rb

Failover to slave1

• shut down master
• stop mongod on slave1, slave2
• backup or delete local.* datafiles on slave1
• restart mongod on slave1 with the --master option
• restart mongod on slave2 with new --source option

Use relica set to simulate master-slave to avoid complicated failover manipulation. Just change configurations

mongo localhost:27018
> config = {
  _id: 'demoMasterSlaveByReplicaSet',
  members: [
    { _id: 0, host: 'localhost:27018', priority: 1 },
    { _id: 1, host: 'localhost:27019', priority: 0, votes: 0 },
    { _id: 2, host: 'localhost:27020', priority: 0, votes: 0 } ]
  }
> rs.initiate(config)