[MongoDB学习笔记二]MongoDB副本集

MongoDB  /  houtizong 发布于 1年前   142

1. 副本集的特性

  1)一台主服务器(Primary),多台从服务器(Secondary)

  2)Primary挂了之后,从服务器自动完成从它们之中选举一台服务器作为主服务器,继续工作,这就解决了单点故障,因此,在这种情况下,MongoDB集群能够继续工作

  3)挂了的主服务器恢复到集群中只能以Secondary服务器的角色加入进来

 

2. 副本集环境搭建

 

 2.1副本集闭环配置(以三台机器配置为例)

 

port=27017bind_ip=127.0.0.1dbpath=/home/tom/development/mongoDBdata/replicaAreplSet=child/127.0.0.1:27018

 

port=27018bind_ip=127.0.0.1dbpath=/home/tom/development/mongoDBdata/replicaBreplSet=child/127.0.0.1:27019

 

port=27019bind_ip=127.0.0.1dbpath=/home/tom/development/mongoDBdata/replicaCreplSet=child/127.0.0.1:27017

 


 2.2 查看副本集状态

rs.status()

 

2.3 启动三台服务器

在~/development/mongoDBConfig目录建立三个配置文件A.conf,B.conf和C.conf,内容分别是上面闭环设置的3台机器的配置,如A.conf的内容是

 

port=27017bind_ip=127.0.0.1dbpath=/home/tom/development/mongoDBdata/replicaAreplSet=child/127.0.0.1:27018

 

在~/devlopment/mongDBConfig目录下,运行命令启动三台服务器

mongd --config A.confmongd --config B.confmongd --config C.conf

 

此时三台服务器都在输出如下类似的日志,不断尝试跟指定的conf文件中指定的child host进行通信(contact),例如27017的

Wed Aug  6 07:26:19.088 [rsStart] trying to contact 127.0.0.1:27018Wed Aug  6 07:26:19.089 [rsStart] replSet can't get local.system.replset config from self or any seed (EMPTYCONFIG)Wed Aug  6 07:26:29.089 [rsStart] trying to contact 127.0.0.1:27018Wed Aug  6 07:26:29.090 [rsStart] replSet can't get local.system.replset config from self or any seed (EMPTYCONFIG)Wed Aug  6 07:26:39.090 [rsStart] trying to contact 127.0.0.1:27018Wed Aug  6 07:26:39.091 [rsStart] replSet can't get local.system.replset config from self or any seed (EMPTYCONFIG)Wed Aug  6 07:26:49.091 [rsStart] trying to contact 127.0.0.1:27018Wed Aug  6 07:26:49.092 [rsStart] replSet can't get local.system.replset config from self or any seed (EMPTYCONFIG)Wed Aug  6 07:26:59.092 [rsStart] trying to contact 127.0.0.1:27018Wed Aug  6 07:26:59.094 [rsStart] replSet can't get local.system.replset config from self or any seed (EMPTYCONFIG)

 

 

Wed Aug  6 07:27:38.614 [rsStart] trying to contact 127.0.0.1:27019Wed Aug  6 07:27:38.615 [rsStart] replSet can't get local.system.replset config from self or any seed (EMPTYCONFIG)Wed Aug  6 07:27:48.615 [rsStart] trying to contact 127.0.0.1:27019Wed Aug  6 07:27:48.616 [rsStart] replSet can't get local.system.replset config from self or any seed (EMPTYCONFIG)Wed Aug  6 07:27:58.616 [rsStart] trying to contact 127.0.0.1:27019Wed Aug  6 07:27:58.617 [rsStart] replSet can't get local.system.replset config from self or any seed (EMPTYCONFIG)Wed Aug  6 07:28:08.617 [rsStart] trying to contact 127.0.0.1:27019Wed Aug  6 07:28:08.618 [rsStart] replSet can't get local.system.replset config from self or any seed (EMPTYCONFIG)Wed Aug  6 07:28:18.618 [rsStart] trying to contact 127.0.0.1:27019Wed Aug  6 07:28:18.619 [rsStart] replSet can't get local.system.replset config from self or any seed (EMPTYCONFIG)

 

 

Wed Aug  6 07:28:35.770 [rsStart] trying to contact 127.0.0.1:27017Wed Aug  6 07:28:35.770 [rsStart] replSet can't get local.system.replset config from self or any seed (EMPTYCONFIG)Wed Aug  6 07:28:45.771 [rsStart] trying to contact 127.0.0.1:27017Wed Aug  6 07:28:45.772 [rsStart] replSet can't get local.system.replset config from self or any seed (EMPTYCONFIG)Wed Aug  6 07:28:55.772 [rsStart] trying to contact 127.0.0.1:27017Wed Aug  6 07:28:55.773 [rsStart] replSet can't get local.system.replset config from self or any seed (EMPTYCONFIG)Wed Aug  6 07:29:05.773 [rsStart] trying to contact 127.0.0.1:27017Wed Aug  6 07:29:05.774 [rsStart] replSet can't get local.system.replset config from self or any seed (EMPTYCONFIG)

 

 2.4 副本集环境初始化

 

上面的日志表明副本集还没有进行初始化,使用如下命令在任意一台服务器的Javascript Shell上运行,完成副本集初始化

 

use admindb.runCommand({"replSetInitiate": {    "_id": "child",    "members": [        {            "_id": 1,            "host": "127.0.0.1:27017"        },        {            "_id": 2,            "host": "127.0.0.1:27018"        },        {            "_id": 3,            "host": "127.0.0.1:27019"        }    ]}});

 此时查看副本集的服务器日志输出,没台机器有如下的日志输出,表明闭环建立成功

Wed Aug  6 07:45:45.954 [initandlisten] connection accepted from 127.0.0.1:46181 #8 (3 connections now open)

 

 rs.status()察看副本集状态,得到如下的输出,可见27017是Primary服务器,其它的是Secodary服务器

child:PRIMARY> rs.status();{"set" : "child","date" : ISODate("2014-08-05T23:56:21Z"),"myState" : 1,"members" : [{"_id" : 1,"name" : "127.0.0.1:27017","health" : 1,"state" : 1,"stateStr" : "PRIMARY","uptime" : 2338,"optime" : Timestamp(1407282254, 1),"optimeDate" : ISODate("2014-08-05T23:44:14Z"),"self" : true},{"_id" : 2,"name" : "127.0.0.1:27018","health" : 1,"state" : 2,"stateStr" : "SECONDARY","uptime" : 722,"optime" : Timestamp(1407282254, 1),"optimeDate" : ISODate("2014-08-05T23:44:14Z"),"lastHeartbeat" : ISODate("2014-08-05T23:56:19Z"),"lastHeartbeatRecv" : ISODate("2014-08-05T23:56:20Z"),"pingMs" : 0,"syncingTo" : "127.0.0.1:27017"},{"_id" : 3,"name" : "127.0.0.1:27019","health" : 1,"state" : 2,"stateStr" : "SECONDARY","uptime" : 720,"optime" : Timestamp(1407282254, 1),"optimeDate" : ISODate("2014-08-05T23:44:14Z"),"lastHeartbeat" : ISODate("2014-08-05T23:56:19Z"),"lastHeartbeatRecv" : ISODate("2014-08-05T23:56:20Z"),"pingMs" : 0,"syncingTo" : "127.0.0.1:27017"}],"ok" : 1}

 

2.5 验证

 

2.5.1.在主服务器27017上执行如下命令:

use foolbardb.persons.insert({"name":"tom"});db.persons.find();>>>{ "_id" : ObjectId("53e1709f07c1625ed566a67f"), "name" : "tom" }

 上面创建了一个数据库foolbar,一个集合persons,插入一条文档,然后执行查询

 

2.5.2.在从服务器27018上执行查询

use foolbardb.persons.find()>>>error: { "$err" : "not master and slaveOk=false", "code" : 13435 }

 

 查询错误,提示27018是Secondary服务器,但是SlaveOk是false,不能做查询操作,所以需要设置从服务器,使之能够支持数据读取操作

 

2.5.3.关掉主服务器27017

那么MongoDB从27018和27019上自动选举一台作为主服务器,此时如果重启27017,那么27017将作为Secondary服务器加入到集群中。假如27019被选举为Primary,那么对27019做针对foolbar数据库persons集合的查询,会查询来1中创建的数据

 

2.5.4.设置读写分离

无论是主从复制还是副本集复制,一方面提供数据的备份,另外一点通过读写分离提高读写性能,在副本集复制方式下,默认情况下,从服务器只进行数据的同步,但是不提供数据读取功能,要想使从服务器提供数据读取功能,需要设置从服务器的slaveOkay为true,但是遗憾的是,如此重要的设置,MongoDB的Javascript Shell竟然没有提供修改的API,难道副本集的本意只做数据同步备份,不做读写分离?It doesn't make any sense!!!要修改slaveOkay,只能通过MongoDB的语言客户端如Java进行修改,这在以后再讲。

 

 

 

请勿发布不友善或者负能量的内容。与人为善,比聪明更重要!

留言需要登陆哦

技术博客集 - 网站简介:
前后端技术:
后端基于Hyperf2.1框架开发,前端使用Bootstrap可视化布局系统生成

网站主要作用:
1.编程技术分享及讨论交流,内置聊天系统;
2.测试交流框架问题,比如:Hyperf、Laravel、TP、beego;
3.本站数据是基于大数据采集等爬虫技术为基础助力分享知识,如有侵权请发邮件到站长邮箱,站长会尽快处理;
4.站长邮箱:514224527@qq.com;

      订阅博客周刊 去订阅

文章归档

文章标签

友情链接

Auther ·HouTiZong
侯体宗的博客
© 2020 zongscan.com
版权所有ICP证 : 粤ICP备20027696号
PHP交流群 也可以扫右边的二维码
侯体宗的博客