5步搞定CentOS6.7上MongoDB副本集搭建

如果只有一个节点或者使用Master-Slave模式,存在主机挂掉后“单点失效的问题。通过使用Mongo DB副本集,可以提高容错性和可用性~~

Areplica setin MongoDB is a group ofmongodprocesses that maintain the same data set. Replica sets provide redundancy and high availability

什么是副本集( Repilca Set )?

副本集在Mongo DB中就是一组mongod维护相同的数据集,副本集提供冗余和高可用~~

一个三个节点的副本集如下图所示:

本篇博文主要给出一个搭建三个节点Mongo DB副本集的示例,只要5个步骤即可~废话不说了,直接来战~~~

第一步 - 准备环境

准备三个虚拟机,其中一个用作Primary,另外两个用作Secondary。如上图展示的那样~

虚拟机信息如下:

Primary -172.xx.xx.107

Secondary -172.xx.xx.105172.xx.xx.106

本文的虚拟机装的是CentOS 6.7 ~

第二步 - yum安装Mongo

本文使用yum install mongodb-org命令来安装。

如果遇到No package mongodb-org available.的问题,如:

Loaded plugins: fastestmirror
Setting up Install Process
Loading mirror speeds from cached hostfile
No package mongodb-org available.
Error: Nothing to do

/etc/yum.repos.d/目录下,创建一个mongodb.repo文件,指定MongoDB资源库即可。

使用vim /etc/yum.repos.d/mongodb.repo命令,创建并打开文件mongodb.repo,

[mongodb-org-3.4]
name=MongoDB Repository
baseurl=https://repo.mongodb.org/yum/redhat/$releasever/mongodb-org/3.4/x86_64/
gpgcheck=1
enabled=1
gpgkey=https://www.mongodb.org/static/pgp/server-3.4.asc

然后,重新使用yum install mongodb-org命令安装即可。

第三步 - 配置副本集

使用vim /etc/mongod.conf配置,每一台虚拟机上的Mongod配置文件。

在replication选项中添加oplogSizeMB 和 replSetName两个属性~

replication:
  oplogSizeMB:  1024
  replSetName:  wang

配置文件mongod.conf如下所示:

# mongod.conf

# for documentation of all options,see:
#   http://docs.mongodb.org/manual/reference/configuration-options/

# where to write logging data.
systemLog:
  destination: file
  logAppend: true
  path: /var/log/mongodb/mongod.log

# Where and how to store data.
storage:
  dbPath: /var/lib/mongo
  journal:
    enabled: true
#  engine:
#  mmapv1:
#  wiredTiger:

# how the process runs
processManagement:
  fork: true  # fork and run in background
  pidFilePath: /var/run/mongodb/mongod.pid  # location of pidfile

# network interfaces
net:
  port: 27017
  bindIp: 0.0.0.0  # Listen to local interface only,comment to listen on all interfaces.


#security:

#operationProfiling:

replication:
  oplogSizeMB:  1024
  replSetName:  wang


#sharding:

## Enterprise-Only Options

#auditLog:

#snmp:

注意:

3台虚拟机,MongoDB配置文件mongod.conf中的replSetName名字要保持一致

在本例中,replSetName的名字为wang,这个名字可以随便取~~

第四步 - 启动

配置好副本集之后,通过mongod --config /etc/mongod.conf命令启动三个虚拟机中的Mongo服务~,如:

[root@dev04 mongodb]# mongod --config /etc/mongod.conf 
about to fork child process,waiting until server is ready for connections.
forked process: 30799
child process started successfully,parent exiting

因为107端口的虚拟机安装的MongoDB要用作Primary节点,所以,我们可以使用mongo命令来连接~

[root@dev04 mongodb]# mongo
MongoDB shell version v3.4.2
connecting to: mongodb://127.0.0.1:27017
MongoDB server version: 3.4.2
Server has startup warnings: 
2017-02-17T09:19:20.240+0800 I STORAGE  [initandlisten] 
2017-02-17T09:19:20.240+0800 I STORAGE  [initandlisten] ** WARNING: Using the XFS filesystem is strongly recommended with the WiredTiger storage engine
2017-02-17T09:19:20.240+0800 I STORAGE  [initandlisten] **          See http://dochub.mongodb.org/core/prodnotes-filesystem
2017-02-17T09:19:20.964+0800 I CONTROL  [initandlisten] 
2017-02-17T09:19:20.964+0800 I CONTROL  [initandlisten] ** WARNING: Access control is not enabled for the database.
2017-02-17T09:19:20.964+0800 I CONTROL  [initandlisten] **          Read and write access to data and configuration is unrestricted.
2017-02-17T09:19:20.964+0800 I CONTROL  [initandlisten] ** WARNING: You are running this process as the root user,which is not recommended.
2017-02-17T09:19:20.965+0800 I CONTROL  [initandlisten] 
2017-02-17T09:19:20.965+0800 I CONTROL  [initandlisten] 
2017-02-17T09:19:20.965+0800 I CONTROL  [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'.
2017-02-17T09:19:20.965+0800 I CONTROL  [initandlisten] **        We suggest setting it to 'never'
2017-02-17T09:19:20.965+0800 I CONTROL  [initandlisten] 
2017-02-17T09:19:20.965+0800 I CONTROL  [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is 'always'.
2017-02-17T09:19:20.965+0800 I CONTROL  [initandlisten] **        We suggest setting it to 'never'
2017-02-17T09:19:20.965+0800 I CONTROL  [initandlisten]

使用use admin,切换到时admin数据库,

> use admin
switched to db admin

然后通过config配置设置副本集节点成员~~

config={_id:"wang",members:[{_id:0,host:"172.xxx.xxx.107:27017"},{_id:1,host:"172.xxx.xxx.106:27017"},{_id:2,host:"172.xxx.xxx.105:27017"}]}

注:

_id:"wang",wang是副本集中取得名字。

members中添加每个副本集Mongod的_id和host信息

执行完上述信息,会出现如下信息:

> config={_id:"wang",host:"172.xxx.xxx.105:27017"}]}
{
	"_id" : "wang","members" : [
		{
			"_id" : 0,"host" : "172.xxx.xxx.107:27017"
		},{
			"_id" : 1,"host" : "172.xxx.xxx.106:27017"
		},{
			"_id" : 2,"host" : "172.xxx.xxx.105:27017"
		}
	]
}
>

然后,执行配置初始化,看到{ "ok" : 1 },则表明初始化成功~

> rs.initiate(config)
{ "ok" : 1 }

使用rs.status()查看副本节点状态~~

wang:PRIMARY> rs.status() 
{
	"set" : "wang","date" : ISODate("2017-02-17T01:30:53.128Z"),"myState" : 1,"term" : NumberLong(1),"heartbeatIntervalMillis" : NumberLong(2000),"optimes" : {
		"lastCommittedOpTime" : {
			"ts" : Timestamp(1487295047,1),"t" : NumberLong(1)
		},"appliedOpTime" : {
			"ts" : Timestamp(1487295047,"durableOpTime" : {
			"ts" : Timestamp(1487295047,"t" : NumberLong(1)
		}
	},"name" : "172.xxx.xxx.107:27017","health" : 1,"state" : 1,"stateStr" : "PRIMARY","uptime" : 693,"optime" : {
				"ts" : Timestamp(1487295047,"t" : NumberLong(1)
			},"optimeDate" : ISODate("2017-02-17T01:30:47Z"),"infoMessage" : "could not find member to sync from","electionTime" : Timestamp(1487294966,"electionDate" : ISODate("2017-02-17T01:29:26Z"),"configVersion" : 1,"self" : true
		},"name" : "172.xxx.xxx.106:27017","state" : 2,"stateStr" : "SECONDARY","uptime" : 96,"optimeDurable" : {
				"ts" : Timestamp(1487295047,"optimeDurableDate" : ISODate("2017-02-17T01:30:47Z"),"lastHeartbeat" : ISODate("2017-02-17T01:30:52.708Z"),"lastHeartbeatRecv" : ISODate("2017-02-17T01:30:51.674Z"),"pingMs" : NumberLong(0),"syncingTo" : "172.xxx.xxx.107:27017","configVersion" : 1
		},"name" : "172.xxx.xxx.105:27017","lastHeartbeatRecv" : ISODate("2017-02-17T01:30:51.745Z"),"syncingTo" : "172.xxx.xxx.106:27017","configVersion" : 1
		}
	],"ok" : 1
}
wang:PRIMARY>

从上图圈出来的信息可以看出,一个Primary 和两个Secondary的副本集已经完成~~~

第五步 - 验证

最后一步就是用来验证了,看看数据能否同步过来~~~

写的操作是在Primary节点上操作的

在107节点上,创建一个messages的数据库,然后在message Collection中插入两条message。

wang:PRIMARY> show dbs
admin  0.000GB
local  0.000GB
wang:PRIMARY> use messages
switched to db messages
wang:PRIMARY> db.message.insert({"name":"This is a test message"})
WriteResult({ "nInserted" : 1 })
wang:PRIMARY> show dbs
admin     0.000GB
local     0.000GB
messages  0.000GB
wang:PRIMARY> db.message.insert({"name":"This is a test message111"})
WriteResult({ "nInserted" : 1 })
wang:PRIMARY>

通过可视化工具查看,Secondary节点105和106上是否可以同步Primary节点107上messages数据库的信息~~

详细信息如下:

从可视化工具的截图可以看出,两个Secondary节点105和106,与Primary节点107,拥有同样的数据集~~ 至此,Mongo DB副本集的环境搭建完成~~~

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