master-slave复制模式大多场景下都被replicat sets代替。官方也建议使用replicat sets。
master-slave复制不支持自动failover。
master-slave部署
1.启动master节点
# ./mongod --master --dbpath /mongodb320/master --port=27017
启动后，会创建local.oplog.$main集合，存放操作日志
2.启动slave节点
# ./mongod --slave --source 12.12.12.195:27017 --dbpath /mongodb320/slave --port=27018
或者启动后设置
# ./mongod --dbpath /mongodb320/slave --port=27018
# ./mongo --port=27018
> use localu
switched to db local
> db.sources.find()
> db.sources.insert({"host":"12.12.12.195:27017"})db.sources.insert({"host":"12.12.12.195:27017"})
WriteResult({ "nInserted" : 1 })
> db.sources.find()
{ "_id" : ObjectId("56e77cfa282f6e26c2c2b5c8"), "host" : "12.12.12.195:27017" }
>
3.查看master-slave状态
#登陆master节点
> rs.printReplicationInfo()
configured oplog size: 1023.9609375MB
log length start to end: 904secs (0.25hrs)
oplog first event time: Tue Mar 15 2016 10:45:17 GMT+0800 (CST)
oplog last event time: Tue Mar 15 2016 11:00:21 GMT+0800 (CST)
now: Tue Mar 15 2016 11:00:27 GMT+0800 (CST)
#登陆slave节点
> rs.printReplicationInfo()
this is a slave, printing slave replication info.
source: 12.12.12.195:27017
syncedTo: Tue Mar 15 2016 11:04:21 GMT+0800 (CST)
6 secs (0 hrs) behind the freshest member (no primary available at the moment)
> rs.printSlaveReplicationInfo()rs.printSlaveReplicationInfo()
source: 12.12.12.195:27017
syncedTo: Tue Mar 15 2016 11:16:21 GMT+0800 (CST)
4 secs (0 hrs) behind the freshest member (no primary available at the moment)
>
mongodb - Master Slave Replication
原文：http://www.cnblogs.com/abclife/p/5278656.html