（案例2）副本集+分片部署

准备四台机器，分别是bluejoe1,bluejoe2,bluejoe3，以及bluejoe0

副本集及分片策略确定如下：

• 将创建3个副本集，命名为shard1,shard2,shard3；
• 以上3个副本集作为3个分片；
• 每个副本集包含3个副本（主、辅1、辅2）；
• 副本分开存储，即shard1存在bluejoe1、bluejoe2、bluejoe3上各一份。。。以此类推
• 将创建3个配置库实例，一台机器一个
• bluejoe0上配置一个mongos（mongos一般可以配置在应用端）

画了一个图：

具体操作步骤如下：

1. 在bluejoe1上下载mongdb安装包；
2. 解压至/usr/local/mongdb（注意改名）；
3. 创建data/db1,db2,db3目录，启动3个mongod实例，注意replSet的名字：
   

    mkdir /usr/local/mongodb/data/db1 /usr/local/mongodb/data/db2 /usr/local/mongodb/data/db3
    nohup /usr/local/mongodb/bin/mongod --dbpath /usr/local/mongodb/data/db1 --port 10001 --replSet db1 --logpath=/usr/local/mongodb/log/db1.log &
    nohup /usr/local/mongodb/bin/mongod --dbpath /usr/local/mongodb/data/db2 --port 10002 --replSet db2 --logpath=/usr/local/mongodb/log/db2.log &
    nohup /usr/local/mongodb/bin/mongod --dbpath /usr/local/mongodb/data/db3 --port 10003 --replSet db3 --logpath=/usr/local/mongodb/log/db3.log &

   
   
4. 使用scp命令，将mongodb目录复制至bluejoe2和bluejoe3机器，并按照第3步启动每台机器上的3个实例；
   
5. 初始化副本：
   

    mongo bluejoe1:10001
   
        use admin
   
        db.runCommand(
        {
            "replSetInitiate":
            {
                "_id":"db1",
                "members":
                [
                    {
                        "_id":1,
                        "host":"bluejoe1:10001"
                    },
                    {
                        "_id":2,
                        "host":"bluejoe2:10001"
                    },
                    {
                        "_id":3,
                        "host":"bluejoe3:10001"
                    }
                ]
            }
        })
   
   
    mongo bluejoe1:10002
   
        use admin
   
        db.runCommand(
        {
            "replSetInitiate":
            {
                "_id":"db2",
                "members":
                [
                    {
                        "_id":1,
                        "host":"bluejoe1:10002"
                    },
                    {
                        "_id":2,
                        "host":"bluejoe2:10002"
                    },
                    {
                        "_id":3,
                        "host":"bluejoe3:10002"
                    }
                ]
            }
        })
   
    mongo bluejoe1:10003
   
        use admin
   
        db.runCommand(
        {
            "replSetInitiate":
            {
                "_id":"db3",
                "members":
                [
                    {
                        "_id":1,
                        "host":"bluejoe1:10003"
                    },
                    {
                        "_id":2,
                        "host":"bluejoe2:10003"
                    },
                    {
                        "_id":3,
                        "host":"bluejoe3:10003"
                    }
                ]
            }
        })

   
   
6. 观察副本集的实时复制特性
   1. 连接上bluejoe1:10001，看到db1:PRIMARY>的字样，说明它是db1的主节点
   2. 创建一张新表，创建几条测试记录
   3. 连接上bluejoe3:10002，看到shard1:SECONDARY>的字样，说明它是shard1的辅助节点
   4. 注意此时无法查询前面新增的记录，会报错not master and slaveOk=false
   5. 回到bluejoe1:10001，设置slaveOk
      

       db.getMongo().setSlaveOk()

   6. 再回到bluejoe3:10002，即可看到主节点写入的记录
      

观察副本集的 故障转移特性

1. 杀掉bluejoe1:10001的进程
2. 再次连接上bluejoe3:10002，看到shard1:PRIMARY>的字样，说明它已经变成shard1的主节点
3. 如果这时再启动bluejoe1:10001，则发现它已经变成shard1:SECONDARY>

创建data/configdb，启动配置库实例：

 mkdir /usr/local/mongodb/data/configdb
 nohup /usr/local/mongodb/bin/mongod --dbpath /usr/local/mongodb/data/configdb --port 20000 --logpath=/usr/local/mongodb/log/configdb.log &

如果需要关闭mongod服务，可使用--shutdown选项，如：

 /usr/local/mongodb/bin/mongod --dbpath /usr/local/mongodb/data/configdb --shutdown

到现在为止应该有12个mongd实例，其中3个为配置库实例，剩下的属于3个副本集；接下来管理分片，在bluejoe0上启动mongs：

 nohup /usr/local/mongodb/bin/mongos --port 30000 --configdb bluejoe1:20000,bluejoe2:20000,bluejoe3:20000 &

连接上mongos，配置分片信息：

 mongo bluejoe0:30000

 mongos> use admin
 switched to db admin

 db.runCommand({"addShard":"db1/bluejoe1:10001"})
 db.runCommand({"addShard":"db2/bluejoe1:10002"})
 db.runCommand({"addShard":"db3/bluejoe1:10003"})

查看分片情况：

 mongos>  db.runCommand({listshards:1})
 {
 <span style="white-space:pre">  span>"shards" : [
 <span style="white-space:pre">      span>{
 <span style="white-space:pre">          span>"_id" : "db1",
 <span style="white-space:pre">          span>"host" : "db1/bluejoe1:10001,bluejoe2:10001,bluejoe3:10001"
 <span style="white-space:pre">      span>},
 <span style="white-space:pre">      span>{
 <span style="white-space:pre">          span>"_id" : "db2",
 <span style="white-space:pre">          span>"host" : "db2/bluejoe1:10002,bluejoe2:10002,bluejoe3:10002"
 <span style="white-space:pre">      span>},
 <span style="white-space:pre">      span>{
 <span style="white-space:pre">          span>"_id" : "db3",
 <span style="white-space:pre">          span>"host" : "db3/bluejoe1:10003,bluejoe2:10003,bluejoe3:10003"
 <span style="white-space:pre">      span>}
 <span style="white-space:pre">  span>],
 <span style="white-space:pre">  span>"ok" : 1
 }

可以看出，尽管注册的时候只是提供了副本集的主节点，但mongos已知晓了各辅助节点；

对某个库开启分片功能：

 mongos> db.runCommand({"enablesharding":"test"})
 { "ok" : 1 }
 mongos> db.runCommand({"shardcollection":"test.person","key":{_id:'hashed'}})
 { "collectionsharded" : "test.person", "ok" : 1 }

插入测试数据：

 mongos> for(var i=0;i<10;i++){db.person.insert({name:"bluejoe"+i});}
 WriteResult({ "nInserted" : 1 })

查看数据分片存储情况：

 [root@hadoop0 ~]# mongo bluejoe3:10002
 MongoDB shell version: 2.6.5
 connecting to: bluejoe3:10002/test
 shard1:PRIMARY> db.person.find()
 { "_id" : ObjectId("546ff1013a0d0ec68b42a914"), "name" : "bluejoe0" }
 { "_id" : ObjectId("546ff1013a0d0ec68b42a915"), "name" : "bluejoe1" }
 { "_id" : ObjectId("546ff1013a0d0ec68b42a91a"), "name" : "bluejoe6" }
 { "_id" : ObjectId("546ff1013a0d0ec68b42a91b"), "name" : "bluejoe7" }
 { "_id" : ObjectId("546ff1013a0d0ec68b42a91c"), "name" : "bluejoe8" }
 shard1:PRIMARY> exit
 bye
 [root@hadoop0 ~]# mongo bluejoe2:10001
 MongoDB shell version: 2.6.5
 connecting to: bluejoe2:10001/test
 shard2:PRIMARY> db.person.find()
 { "_id" : ObjectId("546ff1013a0d0ec68b42a918"), "name" : "bluejoe4" }
 shard2:PRIMARY> exit
 bye
 [root@hadoop0 ~]# mongo bluejoe3:10001
 MongoDB shell version: 2.6.5
 connecting to: bluejoe3:10001/test
 shard3:PRIMARY> db.person.find()
 { "_id" : ObjectId("546ff1013a0d0ec68b42a916"), "name" : "bluejoe2" }
 { "_id" : ObjectId("546ff1013a0d0ec68b42a917"), "name" : "bluejoe3" }
 { "_id" : ObjectId("546ff1013a0d0ec68b42a919"), "name" : "bluejoe5" }
 { "_id" : ObjectId("546ff1013a0d0ec68b42a91d"), "name" : "bluejoe9" }
 shard3:PRIMARY>