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@H_404_4@”@H_404_4@的问题。通过使用Mongo DB副本集,可以提高容错性和可用性@H_404_4@~~
Areplica setin MongoDB is a group of
mongod
processes that maintain the same data set@H_404_4@. Replica sets provide redundancy and high availability@H_404_4@
什么是副本集( Repilca Set )?@H_404_4@
副本集在Mongo DB中就是一组mongod维护相同的数据集@H_404_4@,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~~~
@H_404_4@第一步 - 准备环境@H_404_4@
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@H_404_4@
本文的虚拟机装的是CentOS 6.7 ~@H_404_4@
@H_404_4@第二步 - yum安装Mongo@H_404_4@
本文使用yum install mongodb-org@H_404_4@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
在/etc/yum.repos.d/@H_404_4@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@H_404_4@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。
@H_404_4@第三步 - 配置副本集@H_404_4@
使用vim /etc/mongod.conf@H_404_4@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:
@H_404_4@注意:
3台虚拟机,MongoDB配置文件mongod.conf中的replSetName名字要保持一致@H_404_4@,
在本例中,replSetName的名字为wang,这个名字可以随便取~~
第四步 - 启动@H_404_4@
配置好副本集之后,通过mongod --config /etc/mongod.conf@H_404_4@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@H_404_4@端口的虚拟机安装的MongoDB要用作Primary节点@H_404_4@,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"}]}@H_404_4@
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 }@H_404_4@,则表明初始化成功~
> rs.initiate(config) { "ok" : 1 }
使用rs.status()@H_404_4@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@H_404_4@已经完成~~~
@H_404_4@第五步 - 验证@H_404_4@
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@H_404_4@。
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@H_404_4@上是否可以同步Primary节点107@H_404_4@上messages数据库的信息~~
详细信息如下:
原文链接:https://www.f2er.com/centos/378710.html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@H_404_4@~~ 至此,Mongo DB副本集的环境搭建完成~~~