mongodb集群配置主从模式

• 测试环境

  操作系统：CentOS 7.2 最小化安装

  主服务器IP地址：192.168.197.21 master-node

  从服务器IP地址：192.168.197.22 slave-node

  关闭selinux，关闭防火墙。

  Mongodb版本：mongodb-linux-x86_64-3.4.10.tgz

• 上传mongodb包到/software目录下，然后解压缩该包

  [root@localhost software]# tar -zxvf mongodb-linux-x86_64-3.4.10.tgz

• 移动解压缩之后的文件至/usr/local/mongodb目录

  [root@localhost software]# mv mongodb-linux-x86_64-3.4.10 /usr/local/mongodb

• 在mongodb下面创建data目录和logs目录，用于存放data和logs

  [root@localhost local]# mkdir -p /usr/local/mongodb/data

  [root@localhost local]# mkdir -p /usr/local/mongodb/logs

• 增加环境变量，并使环境变量生效

  [root@localhost data]# vi /etc/profile

  export PATH=$PATH:/usr/local/mongodb/bin

  [root@localhost data]# source /etc/profile

• 创建mongodb.conf文件并写入一下内容

  [root@localhost data]# touch /usr/local/mongodb/bin/mongodb.conf

  [root@localhost data]# vi /usr/local/mongodb/bin/mongodb.conf

• 主服务器配置

  [root@master-node software]# more /usr/local/mongodb/bin/mongodb.conf

  port=27017

  dbpath= /usr/local/mongodb/data

  logpath= /usr/local/mongodb/logs/log.log

  logappend=true

  fork=true

  maxConns=100

  noauth=true

  journal=true

  storageEngine=wiredTiger

  bind_ip = 192.168.197.21

  master=true

• 从服务器配置

  [root@slave-node software]# more /usr/local/mongodb/bin/mongodb.conf

  port=27017

  dbpath= /usr/local/mongodb/data

  logpath= /usr/local/mongodb/logs/log.log

  logappend=true

  fork=true

  maxConns=100

  noauth=true

  slave=true

  journal=true

  storageEngine=wiredTiger

  bind_ip = 192.168.197.22

  source=192.168.197.21:27017

• 使用配置文件启动两台服务器上的数据库

  mongod --config /usr/local/mongodb/bin/mongodb.conf

• 在主服务器上登陆数据库创建testa数据库，并写入20条数据

  [root@master-node software]# mongo 192.168.197.21:27017

  MongoDB shell version v3.4.10

  connecting to: 192.168.197.21:27017

  MongoDB server version: 3.4.10

  Server has startup warnings:

  2019-02-10T21:38:04.484-0500 I CONTROL [initandlisten] ** WARNING: You are running this process as the root user, which is not recommended.

  2019-02-10T21:38:04.484-0500 I CONTROL [initandlisten]

  2019-02-10T21:38:04.485-0500 I CONTROL [initandlisten]

  2019-02-10T21:38:04.485-0500 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'.

  2019-02-10T21:38:04.485-0500 I CONTROL [initandlisten] ** We suggest setting it to 'never'

  2019-02-10T21:38:04.485-0500 I CONTROL [initandlisten]

  2019-02-10T21:38:04.485-0500 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is 'always'.

  2019-02-10T21:38:04.485-0500 I CONTROL [initandlisten] ** We suggest setting it to 'never'

  2019-02-10T21:38:04.485-0500 I CONTROL [initandlisten]

  > use testa

  switched to db testa

  > function add(){var i = 0;for(;i<20;i++){db.persons.insert({"nameA":"li"+i})}}

  > add()

  > db.persons.find()

  { "_id" : ObjectId("5c61272206144917c514f1a3"), "nameA" : "li0" }

  { "_id" : ObjectId("5c61272206144917c514f1a4"), "nameA" : "li1" }

  { "_id" : ObjectId("5c61272206144917c514f1a5"), "nameA" : "li2" }

  { "_id" : ObjectId("5c61272206144917c514f1a6"), "nameA" : "li3" }

  { "_id" : ObjectId("5c61272206144917c514f1a7"), "nameA" : "li4" }

  { "_id" : ObjectId("5c61272206144917c514f1a8"), "nameA" : "li5" }

  { "_id" : ObjectId("5c61272206144917c514f1a9"), "nameA" : "li6" }

  { "_id" : ObjectId("5c61272206144917c514f1aa"), "nameA" : "li7" }

  { "_id" : ObjectId("5c61272206144917c514f1ab"), "nameA" : "li8" }

  { "_id" : ObjectId("5c61272206144917c514f1ac"), "nameA" : "li9" }

  { "_id" : ObjectId("5c61272206144917c514f1ad"), "nameA" : "li10" }

  { "_id" : ObjectId("5c61272206144917c514f1ae"), "nameA" : "li11" }

  { "_id" : ObjectId("5c61272206144917c514f1af"), "nameA" : "li12" }

  { "_id" : ObjectId("5c61272206144917c514f1b0"), "nameA" : "li13" }

  { "_id" : ObjectId("5c61272206144917c514f1b1"), "nameA" : "li14" }

  { "_id" : ObjectId("5c61272206144917c514f1b2"), "nameA" : "li15" }

  { "_id" : ObjectId("5c61272206144917c514f1b3"), "nameA" : "li16" }

  { "_id" : ObjectId("5c61272206144917c514f1b4"), "nameA" : "li17" }

  { "_id" : ObjectId("5c61272206144917c514f1b5"), "nameA" : "li18" }

  { "_id" : ObjectId("5c61272206144917c514f1b6"), "nameA" : "li19" }

• 登陆从服务器的数据库查看数据是否同步过来

  [root@slave-node software]# mongo 192.168.197.22:27017

  MongoDB shell version v3.4.10

  connecting to: 192.168.197.22:27017

  MongoDB server version: 3.4.10

  Server has startup warnings:

  2019-02-10T21:43:16.796-0500 I CONTROL [initandlisten] ** WARNING: You are running this process as the root user, which is not recommended.

  2019-02-10T21:43:16.796-0500 I CONTROL [initandlisten]

  2019-02-10T21:43:16.796-0500 I CONTROL [initandlisten]

  2019-02-10T21:43:16.796-0500 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'.

  2019-02-10T21:43:16.796-0500 I CONTROL [initandlisten] ** We suggest setting it to 'never'

  2019-02-10T21:43:16.796-0500 I CONTROL [initandlisten]

  2019-02-10T21:43:16.796-0500 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is 'always'.

  2019-02-10T21:43:16.796-0500 I CONTROL [initandlisten] ** We suggest setting it to 'never'

  2019-02-10T21:43:16.796-0500 I CONTROL [initandlisten]

  > show dbs

  2019-02-11T02:43:26.999-0500 E QUERY [thread1] Error: listDatabases failed:{

  "ok" : 0,

  "errmsg" : "not master and slaveOk=false",

  "code" : 13435,

  "codeName" : "NotMasterNoSlaveOk"

  } :

  _getErrorWithCode@src/mongo/shell/utils.js:25:13

  Mongo.prototype.getDBs@src/mongo/shell/mongo.js:62:1

  shellHelper.show@src/mongo/shell/utils.js:781:19

  shellHelper@src/mongo/shell/utils.js:671:15

  @(shellhelp2):1:1

  > rs.slaveOk()

  > show dbs

  admin 0.000GB

  local 0.000GB

  master_slave 0.000GB

  testa 0.000GB

  > use testa

  switched to db testa

  > db.persons.find()

  { "_id" : ObjectId("5c61272206144917c514f1a3"), "nameA" : "li0" }

  { "_id" : ObjectId("5c61272206144917c514f1a4"), "nameA" : "li1" }

  { "_id" : ObjectId("5c61272206144917c514f1a5"), "nameA" : "li2" }

  { "_id" : ObjectId("5c61272206144917c514f1a6"), "nameA" : "li3" }

  { "_id" : ObjectId("5c61272206144917c514f1a7"), "nameA" : "li4" }

  { "_id" : ObjectId("5c61272206144917c514f1a8"), "nameA" : "li5" }

  { "_id" : ObjectId("5c61272206144917c514f1a9"), "nameA" : "li6" }

  { "_id" : ObjectId("5c61272206144917c514f1aa"), "nameA" : "li7" }

  { "_id" : ObjectId("5c61272206144917c514f1ab"), "nameA" : "li8" }

  { "_id" : ObjectId("5c61272206144917c514f1ac"), "nameA" : "li9" }

  { "_id" : ObjectId("5c61272206144917c514f1ad"), "nameA" : "li10" }

  { "_id" : ObjectId("5c61272206144917c514f1ae"), "nameA" : "li11" }

  { "_id" : ObjectId("5c61272206144917c514f1af"), "nameA" : "li12" }

  { "_id" : ObjectId("5c61272206144917c514f1b0"), "nameA" : "li13" }

  { "_id" : ObjectId("5c61272206144917c514f1b1"), "nameA" : "li14" }

  { "_id" : ObjectId("5c61272206144917c514f1b2"), "nameA" : "li15" }

  { "_id" : ObjectId("5c61272206144917c514f1b3"), "nameA" : "li16" }

  { "_id" : ObjectId("5c61272206144917c514f1b4"), "nameA" : "li17" }

  { "_id" : ObjectId("5c61272206144917c514f1b5"), "nameA" : "li18" }

  { "_id" : ObjectId("5c61272206144917c514f1b6"), "nameA" : "li19" }

• 关于报错

  如果在slave-node节点上的数据库中查看，有报错："errmsg" : "not master and slaveOk=false"！！！

  首先这是正常的，因为SECONDARY是不允许读写的， 在写多读少的应用中，使用Replica Sets来实现读写分离。通过在连接时指定或者在主库指定slaveOk，由Secondary来分担读的压力，Primary只承担写操作。对于replica set 中的secondary 节点默认是不可读的。

  解决办法：在slave-node节点数据库中执行"rs.slaveOk();"命令即可

  条数据，说明mongodb的主从复制环境已经成功了！当配置完主从服务器后，一但主服务器上的数据发生变化，从服务器也会发生变化。

• 设置mongodb的开机启动。

  首先要在系统服务目录下创建启动文件mongodb.servicer然后写入一下内容

  [root@localhost system]# cd /lib/systemd/system

  [root@localhost system]# vi mongodb.service

  [Unit]

  Description=mongodb

  After=network.target remote-fs.target nss-lookup.target

  [Service]

  Type=forking

  ExecStart=/usr/local/mongodb/bin/mongod -f /usr/local/mongodb/bin/mongodb.conf

  ExecReload=/bin/kill -s HUP $MAINPID

  ExecStop=/usr/local/mongodb/bin/mongod --shutdown

  PrivateTmp=true

  [Install]

  WantedBy=multi-user.target

  注册到开机启动

  [root@localhost system]# systemctl enable mongodb.service

  Created symlink from /etc/systemd/system/multi-user.target.wants/mongodb.service to /usr/lib/systemd/system/mongodb.service.

  启动

  systemctl start mongodb.service

  关闭

  systemctl stop mongodb.service