Replicasets

Introduction

Replica sets is the asynchronous master/slave replication added to Mongodb that takes care off all the failover and recovery for the member nodes. According to the mongodb documentation a replicaset is

• Two or more nodes that are copies of each other
• Automatic assignment of a primary(master) node if none is available
• Drivers that automatically detect the new master and send writes to it

More information at Replicasets

Driver usage

To create a new replicaset follow the instructions on the mongodb site to setup the config and the replicaset instances. Then using the driver.

var replSet = new ReplSet( [
    new Server( 127.0.0.1, 30000),
    new Server( 127.0.0.1, 30001),
    new Server( 127.0.0.1, 30002)
  ],
  {rs_name:RS.name}
);

var db = new Db('integration_test_', replSet);
db.open(function(err, p_db) {
  // Do you app stuff :)
})

The ReplSetSrvers object has the following parameters

var replSet = new ReplSetSrvers(servers, options)

Where

• servers is an array of Server objects
• options can contain the following options

Replicaset options

Several options can be passed to the Replicaset constructor with options parameter.

• rs_name is the name of the replicaset you configured when you started the server, you can have multiple replicasets running on your servers.
• read_secondary set’s the driver to read from secondary servers (slaves) instead of only from the primary(master) server.
• socketOptions - a collection of pr socket settings

Socket options

Several options can be set for the socketOptions .

• timeout = set seconds before connection times out default:0
• noDelay = Disables the Nagle algorithm default:true
• keepAlive = Set if keepAlive is used default:0 , which means no keepAlive, set higher than 0 for keepAlive
• encoding = ‘ascii’|’utf8’|’base64’ default:null