NoSQL 数据库案例实战 --MongoDB 数据库高可用解决方案 -- MongoDB复制集（主从复制）

MongoDB 数据库高可用解决方案 -- MongoDB复制集（主从复制）

• ​​前言​​
• ​​一、什么是MongoDB复制集 ？​​
• ​​二、MongoDB复制集 架构设计​​
• ​​三、MongoDB复制集 实战案例​​

• ​​1、MongoDB复制集部署​​
• ​​2、模拟master故障，实现故障转移、故障恢复​​

前言

本环境是基于 Centos 7.8 系统构建mongodb-enterprise-4.2.8学习环境
具体构建，请参考 ​​mongodb-enterprise-4.2.8 环境构建​​

MongoDB复制是将数据同步到多个服务器的过程；复制集提供了数据的冗余备份并提高了数据的可用性，通常可以保证数据的安全性；复制集还允许技术人员从硬件故障和服务中断中恢复数据。

一、什么是MongoDB复制集 ？

什么是复制集

• 保障数据的安全性
• 数据的冗余、备份
• 数据高可用性 (24*7)
• 灾难恢复
• 无需停机维护（如备份，重建索引，压缩）
• 分布式读取数据
• 副本集对应用层是透明的（相对于终端用户）

MongoDB复制集 工作原理

• 1、mongodb的复制集至少需要两个节点。其中一个是主节点，负责处理客户端请求，其余的都是从节点，负责复制主节点上的数据。
• 2、mongodb各个节点常见的搭配方式为：一主一从、一主多从。
• 3、主节点记录在其上的所有操作oplog，从节点定期轮询主节点获取这些操作，然后对自己的数据副本执行这些操作，从而保证从节点的数据与主节点一致

二、MongoDB复制集 架构设计

MongoDB 复制集的特点

• N 个节点的集群
• 任何节点可作为主节点
• 所有写入操作都在主节点上
• 自动故障转移
• 自动恢复

三、MongoDB复制集 实战案例

1、MongoDB复制集部署

环境准备

修改MongoDB配置文件

# 所有节点修改
--- node01
[root@node01 ~]# vim /etc/mongod.conf
net:
  port: 27017
  bindIp: 127.0.0.1,192.168.5.11
replication:
  oplogSizeMB: 1024
  replSetName: myRs
[root@node01 ~]# systemctl restart mongod

--- node02
[root@node02 ~]# vim /etc/mongod.conf
net:
  port: 27017
  bindIp: 127.0.0.1,192.168.5.12
replication:
  oplogSizeMB: 1024
  replSetName: myRs
[root@node02 ~]# systemctl restart mongod
  
--- node03
[root@node03 ~]# vim /etc/mongod.conf
net:
  port: 27017
  bindIp: 127.0.0.1,192.168.5.13
replication:
  oplogSizeMB: 1024
  replSetName: myRs
[root@node03 ~]# systemctl restart mongod

配置主节点

# 登录MongoDB
[root@node01 ~]# mongo
MongoDB shell version v4.2.8

# 查看ReplSet状态
MongoDB Enterprise > rs.status()
{
  "operationTime" : Timestamp(0, 0),
  "ok" : 0,
  "errmsg" : "no replset config has been received",
  "code" : 94,
  "codeName" : "NotYetInitialized",
  "$clusterTime" : {
    "clusterTime" : Timestamp(0, 0),
    "signature" : {
      "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
      "keyId" : NumberLong(0)
    }
  }
}

# 初始化ReplSet复制集
MongoDB Enterprise > rs.initiate({_id:'myRS',members:[{_id:1,host:'192.168.5.11:27017'}]})
{
  "ok" : 1,
  "$clusterTime" : {
    "clusterTime" : Timestamp(1613533287, 1),
    "signature" : {
      "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
      "keyId" : NumberLong(0)
    }
  },
  "operationTime" : Timestamp(1613533287, 1)
}

再次查看ReplSet状态

主上增加从节点

MongoDB Enterprise myRS:PRIMARY> rs.add('192.168.5.12:27017','192.168.5.13:27017')
{
  "ok" : 1,
  "$clusterTime" : {
    "clusterTime" : Timestamp(1613534429, 1),
    "signature" : {
      "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
      "keyId" : NumberLong(0)
    }
  },
  "operationTime" : Timestamp(1613534429, 1)
}

查看ReplSet状态

主节点插入数据，测试主从同步

主插入数据

# 插入数据
MongoDB Enterprise myRS:PRIMARY> use test
switched to db test

MongoDB Enterprise myRS:PRIMARY> for(var i =0; i <4; i ++){db.user.insert({userName:'my'+i,age:i})}
WriteResult({ "nInserted" : 1 })

# 查看数据
MongoDB Enterprise myRS:PRIMARY> db.user.find()
{ "_id" : ObjectId("602c98c21b314e8e6e90e15a"), "userName" : "my0", "age" : 0 }
{ "_id" : ObjectId("602c98c21b314e8e6e90e15b"), "userName" : "my1", "age" : 1 }
{ "_id" : ObjectId("602c98c21b314e8e6e90e15c"), "userName" : "my2", "age" : 2 }
{ "_id" : ObjectId("602c98c21b314e8e6e90e15d"), "userName" : "my3", "age" : 3 }

slave01查看

slave02查看

MongoDB复制集成功！！！

2、模拟master故障，实现故障转移、故障恢复

模拟关闭主节点

MongoDB Enterprise myRS:PRIMARY> use admin
switched to db admin
MongoDB Enterprise myRS:PRIMARY> db.shutdownServer()
2021-02-17T12:30:51.021+0800 I  NETWORK  [js] DBClientConnection failed to receive message from 127.0.0.1:27017 - HostUnreachable: Connection closed by peer
server should be down...
2021-02-17T12:30:51.038+0800 I  NETWORK  [js] trying reconnect to 127.0.0.1:27017 failed
2021-02-17T12:30:51.038+0800 I  NETWORK  [js] reconnect 127.0.0.1:27017 failed failed 
2021-02-17T12:30:51.042+0800 I  NETWORK  [js] trying reconnect to 127.0.0.1:27017 failed
2021-02-17T12:30:51.042+0800 I  NETWORK  [js] reconnect 127.0.0.1:27017 failed failed 
MongoDB Enterprise >

node03查看

node02切换为master

node02查看插入三条记录

[root@node02 ~]# mongo
MongoDB shell version v4.2.8
MongoDB Enterprise myRS:PRIMARY> use test
switched to db test
MongoDB Enterprise myRS:PRIMARY> for(var i =4; i <7; i ++){db.user.insert({userName:'my'+i,age:i})}
WriteResult({ "nInserted" : 1 })
MongoDB Enterprise myRS:PRIMARY> db.user.find()
{ "_id" : ObjectId("602c98c21b314e8e6e90e15a"), "userName" : "my0", "age" : 0 }
{ "_id" : ObjectId("602c98c21b314e8e6e90e15b"), "userName" : "my1", "age" : 1 }
{ "_id" : ObjectId("602c98c21b314e8e6e90e15c"), "userName" : "my2", "age" : 2 }
{ "_id" : ObjectId("602c98c21b314e8e6e90e15d"), "userName" : "my3", "age" : 3 }
{ "_id" : ObjectId("602c9d4a2db6914f63068e15"), "userName" : "my4", "age" : 4 }
{ "_id" : ObjectId("602c9d4a2db6914f63068e16"), "userName" : "my5", "age" : 5 }
{ "_id" : ObjectId("602c9d4a2db6914f63068e17"), "userName" : "my6", "age" : 6 }

node03查看

启动master

[root@node01 ~]# systemctl start mongod
[root@node01 ~]# systemctl is-active mongod
active

node03查看主从状态

node01已经切换到salve状态

node02再次插入三条数据

MongoDB Enterprise myRS:PRIMARY> use test
switched to db test
MongoDB Enterprise myRS:PRIMARY> for(var i =7; i <10; i ++){db.user.insert({userName:'my'+i,age:i})}
WriteResult({ "nInserted" : 1 })
MongoDB Enterprise myRS:PRIMARY> db.user.find()
{ "_id" : ObjectId("602c98c21b314e8e6e90e15a"), "userName" : "my0", "age" : 0 }
{ "_id" : ObjectId("602c98c21b314e8e6e90e15b"), "userName" : "my1", "age" : 1 }
{ "_id" : ObjectId("602c98c21b314e8e6e90e15c"), "userName" : "my2", "age" : 2 }
{ "_id" : ObjectId("602c98c21b314e8e6e90e15d"), "userName" : "my3", "age" : 3 }
{ "_id" : ObjectId("602c9d4a2db6914f63068e15"), "userName" : "my4", "age" : 4 }
{ "_id" : ObjectId("602c9d4a2db6914f63068e16"), "userName" : "my5", "age" : 5 }
{ "_id" : ObjectId("602c9d4a2db6914f63068e17"), "userName" : "my6", "age" : 6 }
{ "_id" : ObjectId("602c9f71912509e6bd44076c"), "userName" : "my7", "age" : 7 }
{ "_id" : ObjectId("602c9f71912509e6bd44076d"), "userName" : "my8", "age" : 8 }
{ "_id" : ObjectId("602c9f71912509e6bd44076e"), "userName" : "my9", "age" : 9 }

node01查看数据

node03查看数据

故障切换、故障恢复成功实现！！！