MongoDB Replica Set 副本集实践

2018-04-26 本文已影响0人 CoderMiner

在自己的本机创建有三个节点的副本集 (一个主节点，两个从节点)，是基于MongoDB 3.6 版本

创建数据存储路径
```
mkdir r0
mkdir r1
mkdir r2
```
创建log存储路径
```
mkdir log
```

启动第一个节点

mongod --replSet rs0 --port 27017 --bind_ip 127.0.0.1 --dbpath .\r0\ --logpath log\r0.log --logappend

启动第二个节点

mongod --replSet rs0 --port 27018 --bind_ip 127.0.0.1 --dbpath .\r1\ --logpath log\r1.log --logappend

启动第三个节点

mongod --replSet rs0 --port 27017 --bind_ip 127.0.0.1 --dbpath .\r2\ --logpath log\r2.log --logappend

连接到 mongod 实例
```
mongo --port 27017
```
在 mongo shell中，使用 rs.initiate() 初始化副本集

rsconf = {
  _id: "rs0",
  members: [
    {
     _id: 0,
     host: "127.0.1:27017"
    },
    {
     _id: 1,
     host: "127.0.1:27018"
    },
    {
     _id: 2,
     host: "127.0.1:27019"
    }
   ]
}
rs.initiate(rsconf)

初始化成功

{
        "ok" : 1,
        "operationTime" : Timestamp(1524728214, 1),
        "$clusterTime" : {
                "clusterTime" : Timestamp(1524728214, 1),
                "signature" : {
                        "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
                        "keyId" : NumberLong(0)
                }
        }
}

查看副本集的状态
27017:是主节点
27018 27019是从节点

rs.status()
{
      "set" : "rs0",
      "date" : ISODate("2018-04-26T08:15:11.241Z"),
      "myState" : 1,
      ...
      "members" : [
              {
                      "_id" : 0,
                      "name" : "127.0.0.1:27017",
                      "health" : 1,
                      "state" : 1,
                      "stateStr" : "PRIMARY",
                      ...
              },
              {
                      "_id" : 1,
                      "name" : "127.0.0.1:27018",
                      "health" : 1,
                      "state" : 2,
                      "stateStr" : "SECONDARY",
                       ...
              },
              {
                      "_id" : 2,
                      "name" : "127.0.0.1:27019",
                      "health" : 1,
                      "state" : 2,
                      "stateStr" : "SECONDARY",
                      ...
              }
      ],
      "ok" : 1,
      ...
  }

查看节点是否是主节点

rs.isMaster()
{
                "hosts" : [
                        "127.0.0.1:27017",
                        "127.0.0.1:27018",
                        "127.0.0.1:27019"
                ],
                "setName" : "rs0",
                "setVersion" : 1,
                "ismaster" : true,
                "secondary" : false,
                "primary" : "127.0.0.1:27017",
                "me" : "127.0.0.1:27017",
                "electionId" : ObjectId("7fffffff0000000000000003"),
               ...
        }

读写操作
先在主节点创建一个数据库并写入数据

use TestDB  
db.createCollection("TestModel")  
db.getCollection("TestModel").insert({"first_name":"Lorry","second_name":"kevin"})

使用从节点进行查询

mongo --port 27019

无法进行查询的操作 ,从节点无法进行查询操作

rs0:SECONDARY> show dbs
2018-04-26T16:20:35.769+0800 E QUERY    [thread1] Error: listDatabases failed:{
      "operationTime" : Timestamp(1524730833, 1),
      "ok" : 0,
      "errmsg" : "not master and slaveOk=false",
      "code" : 13435,
      "codeName" : "NotMasterNoSlaveOk",
      ...
} :

配置从节点可以进行查询

db.getMongo().setSlaveOk()

rs0:SECONDARY> show dbs
TestDB  0.000GB
admin   0.000GB
config  0.000GB
local   0.000GB

故障转移

把主节点端口停掉，再查看对应的副本集的状态
rs.status()

  27017 ： "stateStr" : "(not reachable/healthy)"  
  27018 ： "stateStr" : "PRIMARY",  
  27019 : "stateStr" : "SECONDARY",  

  27018 变成了主节点  
 {
        "set" : "rs0",
        "date" : ISODate("2018-04-26T08:24:24.740Z"),
        "myState" : 2,
        "term" : NumberLong(4),
        ...
        "members" : [
                {
                        "_id" : 0,
                        "name" : "127.0.0.1:27017",
                        "health" : 0,
                        "state" : 8,
                        "stateStr" : "(not reachable/healthy)",
                        ...
                },
                {
                        "_id" : 1,
                        "name" : "127.0.0.1:27018",
                        "health" : 1,
                        "state" : 1,
                        "stateStr" : "PRIMARY",
                        ...
                },
                {
                        "_id" : 2,
                        "name" : "127.0.0.1:27019",
                        "health" : 1,
                        "state" : 2,
                        "stateStr" : "SECONDARY",
                       ...
                }
        ],
        "ok" : 1,
        ...
}

增加节点
```
mkdir r3
```

启动新节点

mongod --relpSet rs0 --port 27020 --bind_ip 127.0.0.1 --dbpath .\r3\

增加节点

rs.add("127.0.0.1:27020")
{
      "ok" : 1,
      "operationTime" : Timestamp(1524731467, 1),
      "$clusterTime" : {
              "clusterTime" : Timestamp(1524731467, 1),
              "signature" : {
                      "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
                      "keyId" : NumberLong(0)
              }
      }
}

在查看副本集的状态，可以看到 27020的新节点，连接到新的节点查看，数据已经同步了

删除节点

rs.remove("127.0.0.1:27020")

  {
          "ok" : 1,
          "operationTime" : Timestamp(1524731753, 1),
          "$clusterTime" : {
                  "clusterTime" : Timestamp(1524731753, 1),
                  "signature" : {
                          "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
                          "keyId" : NumberLong(0)
                  }
          }
  }

再查看一下当前副本集的状态，可以看到 27020的节点已经被删除了

MongoDB Replica Set 副本集实践

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