MongoDB副本集搭建

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一、环境

$ cat /etc/redhat-release 
CentOS Linux release 7.0.1406 (Core) 
$ uname -a
Linux zhaopin-2-201 3.10.0-123.el7.x86_64 #1 SMP Mon Jun 30 12:09:22 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
$ mongo --version
MongoDB shell version: 3.0.6

二、准备

1.创建目录

$ sudo mkdir -p /data/mongodb/{data/db0,backup/db0,log/db0,conf/db0}

2.编写配置文件

$ sudo vim /data/mongodb/conf/db0/mongodb.conf
# base
port = 27017
maxConns = 800 
filePermissions = 0700
fork = true
noauth = true
dbpath = /data/mongodb/data/db0
pidfilepath = /data/mongodb/data/db0/mongodb.pid
journal = true
# security
nohttpinterface = true
rest = false
# log 
logpath = /data/mongodb/log/db0/mongodb.log
logRotate = rename
logappend = true
slowms = 50
replSet = rs0

三、配置副本集

1.配置primary

1）启动

$ sudo /opt/mongodb/bin/mongod --config /data/mongodb/conf/db0/mongodb.conf  
about to fork child process, waiting until server is ready for connections.
forked process: 48583
child process started successfully, parent exiting
$ mongo
MongoDB shell version: 3.0.6
connecting to: test
> rs.status();
{
        "info" : "run rs.initiate(...) if not yet done for the set",
        "ok" : 0,
        "errmsg" : "no replset config has been received",
        "code" : 94
}

2）初始化

> cfg={_id:"rs0", members:[ {_id:0,host:"172.30.2.201:27017"}] }
{
        "_id" : "rs0",
        "members" : [
                {
                        "_id" : 0,
                        "host" : "172.30.2.201:27017"
                }
        ]
}
> rs.initiate( cfg );
{ "ok" : 1 }
rs0:OTHER> rs.status();
{
        "set" : "rs0",
        "date" : ISODate("2015-09-25T08:31:36.354Z"),
        "myState" : 1,
        "members" : [
                {
                        "_id" : 0,
                        "name" : "172.30.2.201:27017",
                        "health" : 1,
                        "state" : 1,
                        "stateStr" : "PRIMARY",
                        "uptime" : 112,
                        "optime" : Timestamp(1443169891, 1),
                        "optimeDate" : ISODate("2015-09-25T08:31:31Z"),
                        "electionTime" : Timestamp(1443169891, 2),
                        "electionDate" : ISODate("2015-09-25T08:31:31Z"),
                        "configVersion" : 1,
                        "self" : true
                }
        ],
        "ok" : 1
}

2.添加节点

1）启动新的节点

$ sudo /opt/mongodb/bin/mongod --config /data/mongodb/conf/db0/mongodb.conf
about to fork child process, waiting until server is ready for connections.
forked process: 41794
child process started successfully, parent exiting
$ sudo /opt/mongodb/bin/mongod --config /data/mongodb/conf/db0/mongodb.conf
about to fork child process, waiting until server is ready for connections.
forked process: 3761
child process started successfully, parent exiting

2）添加新的节点

在primary上执行：

rs0:PRIMARY> rs.add( "172.30.2.202:27017" );
{ "ok" : 1 }
rs0:PRIMARY> rs.status();
{
        "set" : "rs0",
        "date" : ISODate("2015-09-25T08:34:48.161Z"),
        "myState" : 1,
        "members" : [
                {
                        "_id" : 0,
                        "name" : "172.30.2.201:27017",
                        "health" : 1,
                        "state" : 1,
                        "stateStr" : "PRIMARY",
                        "uptime" : 304,
                        "optime" : Timestamp(1443170060, 1),
                        "optimeDate" : ISODate("2015-09-25T08:34:20Z"),
                        "electionTime" : Timestamp(1443169891, 2),
                        "electionDate" : ISODate("2015-09-25T08:31:31Z"),
                        "configVersion" : 2,
                        "self" : true
                },
                {
                        "_id" : 1,
                        "name" : "172.30.2.202:27017",
                        "health" : 1,
                        "state" : 2,
                        "stateStr" : "SECONDARY",
                        "uptime" : 27,
                        "optime" : Timestamp(1443170060, 1),
                        "optimeDate" : ISODate("2015-09-25T08:34:20Z"),
                        "lastHeartbeat" : ISODate("2015-09-25T08:34:46.884Z"),
                        "lastHeartbeatRecv" : ISODate("2015-09-25T08:34:46.896Z"),
                        "pingMs" : 0,
                        "configVersion" : 2
                }
        ],
        "ok" : 1
}
rs0:PRIMARY> rs.add( "172.30.2.203:27017" );
{ "ok" : 1 }
rs0:PRIMARY> rs.status();
{
        "set" : "rs0",
        "date" : ISODate("2015-09-25T08:36:22.579Z"),
        "myState" : 1,
        "members" : [
                {
                        "_id" : 0,
                        "name" : "172.30.2.201:27017",
                        "health" : 1,
                        "state" : 1,
                        "stateStr" : "PRIMARY",
                        "uptime" : 398,
                        "optime" : Timestamp(1443170158, 1),
                        "optimeDate" : ISODate("2015-09-25T08:35:58Z"),
                        "electionTime" : Timestamp(1443169891, 2),
                        "electionDate" : ISODate("2015-09-25T08:31:31Z"),
                        "configVersion" : 3,
                        "self" : true
                },
                {
                        "_id" : 1,
                        "name" : "172.30.2.202:27017",
                        "health" : 1,
                        "state" : 2,
                        "stateStr" : "SECONDARY",
                        "uptime" : 121,
                        "optime" : Timestamp(1443170158, 1),
                        "optimeDate" : ISODate("2015-09-25T08:35:58Z"),
                        "lastHeartbeat" : ISODate("2015-09-25T08:36:22.268Z"),
                        "lastHeartbeatRecv" : ISODate("2015-09-25T08:36:20.949Z"),
                        "pingMs" : 0,
                        "syncingTo" : "172.30.2.201:27017",
                        "configVersion" : 3
                },
                {
                        "_id" : 2,
                        "name" : "172.30.2.203:27017",
                        "health" : 1,
                        "state" : 2,
                        "stateStr" : "SECONDARY",
                        "uptime" : 24,
                        "optime" : Timestamp(1443170158, 1),
                        "optimeDate" : ISODate("2015-09-25T08:35:58Z"),
                        "lastHeartbeat" : ISODate("2015-09-25T08:36:22.267Z"),
                        "lastHeartbeatRecv" : ISODate("2015-09-25T08:36:22.275Z"),
                        "pingMs" : 0,
                        "configVersion" : 3
                }
        ],
        "ok" : 1
}

四、验证

1.数据同步

1) primary：

$ mongo
MongoDB shell version: 3.0.6
connecting to: test
rs0:PRIMARY> use aaa;
switched to db aaa
rs0:PRIMARY> db.createCollection( "test" );
{ "ok" : 1 }
rs0:PRIMARY> show collections;
system.indexes
test

2) secondary：

$ mongo
MongoDB shell version: 3.0.6
connecting to: test
rs0:SECONDARY> rs.slaveOk();
rs0:SECONDARY> use aaa;
switched to db aaa
rs0:SECONDARY> show collections;
system.indexes
test
$ mongo
MongoDB shell version: 3.0.6
connecting to: test
rs0:SECONDARY> rs.slaveOk();
rs0:SECONDARY> use aaa;
switched to db aaa
rs0:SECONDARY> show collections;
system.indexes
test

2.读写验证

由上可知，primary是可读写的

在secondary上写测试：

$ mongo
MongoDB shell version: 3.0.6
connecting to: test
> use aaa;
switched to db aaa
> db.createCollection("test2");
{ "note" : "from execCommand", "ok" : 0, "errmsg" : "not master" }
> show collections;
2015-09-23T15:57:49.240+0800 E QUERY    Error: listCollections failed: { "note" : "from execCommand", "ok" : 0, "errmsg" : "not master" }
    at Error (<anonymous>)
    at DB._getCollectionInfosCommand (src/mongo/shell/db.js:646:15)
    at DB.getCollectionInfos (src/mongo/shell/db.js:658:20)
    at DB.getCollectionNames (src/mongo/shell/db.js:669:17)
    at shellHelper.show (src/mongo/shell/utils.js:625:12)
    at shellHelper (src/mongo/shell/utils.js:524:36)
    at (shellhelp2):1:1 at src/mongo/shell/db.js:646
> rs.slaveOk();
> show collections;
system.indexes
test
>

证明secondary节点是不能写，默认也是不可读的，需要执行rs.slaveOk();或者db.getMongo().setSlaveOk();并且只对当前session有效，所以每次连接从库都需要执行。

五、说明

mongodb的副本集至少需要3台以上才能实现高可用，并且节点的个数最好是基数。

MongoDB副本集搭建

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原文地址：http://my.oschina.net/u/2426299/blog/511285