关于CentOS 8 搭建MongoDB4.4分片集群的问题

一，简介

1.分片

在mongodb里面存在另一种集群，就是分片技术，可以满足mongodb数据量大量增长的需求。
在mongodb存储海量数据时，一台机器可能不足以存储数据，也可能不足以提供可接受的读写吞吐量。这时，我们就可以通过在多台机器上分割数据，使得数据库系统能存储和处理更多的数据。

2.为什么使用分片

• 复制所有的写入操作到主节点
• 延迟的敏感数据会在主节点查询
• 单个副本集限制在12个节点
• 当请求量巨大时会出现内存不足
• 本地磁盘不足
• 垂直扩展价格昂贵

3.分片原理概述

分片就是把数据分成块，再把块存储到不同的服务器上，mongodb的分片是自动分片的，当用户发送读写数据请求的时候，先经过mongos这个路由层，mongos路由层去配置服务器请求分片的信息，再来判断这个请求应该去哪一台服务器上读写数据。

二，准备环境

• 操作系统：centos linux release 8.2.2004 (core)
• mongodb版本：v4.4.10
• ip：10.0.0.56 实例：mongos（30000） config（27017） shard1主节点（40001） shard2仲裁节点（40002） shard3副节点（40003）
• ip：10.0.0.57 实例：mongos（30000） config（27017） shard1副节点（40001） shard2主节点（40002） shard3仲裁节点（40003）
• ip：10.0.0.58 实例：mongos（30000） config（27017） shard1仲裁节点（40001） shard3副节点（40002） shard3主节点（40003）

三，集群配置部署

1.创建相应目录（三台服务器执行相同操作）

mkdir -p /mongo/{data,logs,apps,run}
mkdir -p /mongo/data/shard{1,2,3}
mkdir -p /mongo/data/config
mkdir -p /mongo/apps/conf

2.安装mongodb修改创建配置文件（三台执行相同操作）

安装可以通过下载mongodb安装包，再进行配置环境变量。这里是直接配置yum源，通过yum源安装的mongodb，后面直接执行mongod加所需配置文件路径运行即可。

（1）mongo-config配置文件

vim /mongo/apps/conf/mongo-config.yml

systemlog:
  destination: file
#日志路径
  path: "/mongo/logs/mongo-config.log"
  logappend: true
storage:
  journal:
    enabled: true
#数据存储路径
  dbpath: "/mongo/data/config"
  engine: wiredtiger
  wiredtiger:
    engineconfig:
         cachesizegb: 12
processmanagement:
  fork: true
  pidfilepath: "/mongo/run/mongo-config.pid"
net:
#这里ip可以设置为对应主机ip
  bindip: 0.0.0.0
#端口
  port: 27017
setparameter:
  enablelocalhostauthbypass: true
replication:
#复制集名称
  replsetname: "mgconfig"
sharding:
#作为配置服务
  clusterrole: configsvr

（2）mongo-shard1配置文件

vim /mongo/apps/conf/mongo-shard1.yml

systemlog:
  destination: file
  path: "/mongo/logs/mongo-shard1.log"
  logappend: true
storage:
  journal:
    enabled: true
  dbpath: "/mongo/data/shard1"
processmanagement:
  fork: true
  pidfilepath: "/mongo/run/mongo-shard1.pid"
net:
  bindip: 0.0.0.0
  #注意修改端口
  port: 40001
setparameter:
  enablelocalhostauthbypass: true
replication:
  #复制集名称
  replsetname: "shard1"
sharding:
  #作为分片服务
  clusterrole: shardsvr

（3）mongo-shard2配置文件

vim /mongo/apps/conf/mongo-shard2.yml

systemlog:
  destination: file
  path: "/mongo/logs/mongo-shard2.log"
  logappend: true
storage:
  journal:
    enabled: true
  dbpath: "/mongo/data/shard2"
processmanagement:
  fork: true
  pidfilepath: "/mongo/run/mongo-shard2.pid"
net:
  bindip: 0.0.0.0
  #注意修改端口
  port: 40002
setparameter:
  enablelocalhostauthbypass: true
replication:
  #复制集名称
  replsetname: "shard2"
sharding:
  #作为分片服务
  clusterrole: shardsvr

（4）mongo-shard3配置文件

vim /mongo/apps/conf/mongo-shard3.yml

systemlog:
  destination: file
  path: "/mongo/logs/mongo-shard3.log"
  logappend: true
storage:
  journal:
    enabled: true
  dbpath: "/mongo/data/shard3"
processmanagement:
  fork: true
  pidfilepath: "/mongo/run/mongo-shard3.pid"
net:
  bindip: 0.0.0.0
  #注意修改端口
  port: 40003
setparameter:
  enablelocalhostauthbypass: true
replication:
  #复制集名称
  replsetname: "shard3"
sharding:
  #作为分片服务
  clusterrole: shardsvr

（5）mongo-route配置文件

vim /mongo/apps/conf/mongo-route.yml

systemlog:
  destination: file
  #注意修改路径
  path: "/mongo/logs/mongo-route.log"
  logappend: true
processmanagement:
  fork: true
  pidfilepath: "/mongo/run/mongo-route.pid"
net:
  bindip: 0.0.0.0
  #注意修改端口
  port: 30000
setparameter:
  enablelocalhostauthbypass: true
replication:
  localpingthresholdms: 15
sharding:
  #关联配置服务
  configdb: mgconfig/10.0.0.56:27017,10.0.0.57:27017,10.0.0.58:27018

3.启动mongo-config服务（三台服务器执行相同操作）

#关闭之前yum安装的mongodb
systemctl stop mongod

cd /mongo/apps/conf/
mongod --config mongo-config.yml

#查看端口27017是否启动
netstat -ntpl
active internet connections (only servers)
proto recv-q send-q local address           foreign address         state       pid/program name
tcp        0      0 0.0.0.0:22              0.0.0.0:*               listen      1129/sshd
tcp        0      0 127.0.0.1:631           0.0.0.0:*               listen      1131/cupsd
tcp        0      0 127.0.0.1:6010          0.0.0.0:*               listen      2514/sshd: root@pts
tcp        0      0 127.0.0.1:6011          0.0.0.0:*               listen      4384/sshd: root@pts
tcp        0      0 0.0.0.0:27017           0.0.0.0:*               listen      4905/mongod
tcp        0      0 0.0.0.0:111             0.0.0.0:*               listen      1/systemd
tcp6       0      0 :::22                   :::*                    listen      1129/sshd
tcp6       0      0 ::1:631                 :::*                    listen      1131/cupsd
tcp6       0      0 ::1:6010                :::*                    listen      2514/sshd: root@pts
tcp6       0      0 ::1:6011                :::*                    listen      4384/sshd: root@pts
tcp6       0      0 :::111                  :::*                    listen      1/systemd

4.连接一台实例，创建初始化复制集

#连接mongo
mongo 10.0.0.56:27017

#配置初始化复制集，这里的mgconfig要和配置文件里的replset的名称一致
config={_id:"mgconfig",members:[ 
  {_id:0,host:"10.0.0.56:27017"},
  {_id:1,host:"10.0.0.57:27017"},
  {_id:2,host:"10.0.0.58:27017"}, 
]}

rs.initiate(config)
#ok返回1便是初始化成功
{
	"ok" : 1,
	"$glestats" : {
		"lastoptime" : timestamp(1634710950, 1),
		"electionid" : objectid("000000000000000000000000")
	},
	"lastcommittedoptime" : timestamp(0, 0)
}

#检查状态
rs.status()

{
	"set" : "mgconfig",
	"date" : isodate("2021-10-20t06:24:24.277z"),
	"mystate" : 1,
	"term" : numberlong(1),
	"syncsourcehost" : "",
	"syncsourceid" : -1,
	"configsvr" : true,
	"heartbeatintervalmillis" : numberlong(2000),
	"majorityvotecount" : 2,
	"writemajoritycount" : 2,
	"votingmemberscount" : 3,
	"writablevotingmemberscount" : 3,
	"optimes" : {
		"lastcommittedoptime" : {
			"ts" : timestamp(1634711063, 1),
			"t" : numberlong(1)
		},
		"lastcommittedwalltime" : isodate("2021-10-20t06:24:23.811z"),
		"readconcernmajorityoptime" : {
			"ts" : timestamp(1634711063, 1),
			"t" : numberlong(1)
		},
		"readconcernmajoritywalltime" : isodate("2021-10-20t06:24:23.811z"),
		"appliedoptime" : {
			"ts" : timestamp(1634711063, 1),
			"t" : numberlong(1)
		},
		"durableoptime" : {
			"ts" : timestamp(1634711063, 1),
			"t" : numberlong(1)
		},
		"lastappliedwalltime" : isodate("2021-10-20t06:24:23.811z"),
		"lastdurablewalltime" : isodate("2021-10-20t06:24:23.811z")
	},
	"laststablerecoverytimestamp" : timestamp(1634711021, 1),
	"electioncandidatemetrics" : {
		"lastelectionreason" : "electiontimeout",
		"lastelectiondate" : isodate("2021-10-20t06:22:41.335z"),
		"electionterm" : numberlong(1),
		"lastcommittedoptimeatelection" : {
			"ts" : timestamp(0, 0),
			"t" : numberlong(-1)
		},
		"lastseenoptimeatelection" : {
			"ts" : timestamp(1634710950, 1),
			"t" : numberlong(-1)
		},
		"numvotesneeded" : 2,
		"priorityatelection" : 1,
		"electiontimeoutmillis" : numberlong(10000),
		"numcatchupops" : numberlong(0),
		"newtermstartdate" : isodate("2021-10-20t06:22:41.509z"),
		"wmajoritywriteavailabilitydate" : isodate("2021-10-20t06:22:42.322z")
	},
	"members" : [
		{
			"_id" : 0,
			"name" : "10.0.0.56:27017",
			"health" : 1,
			"state" : 1,
			"statestr" : "primary",
			"uptime" : 530,
			"optime" : {
				"ts" : timestamp(1634711063, 1),
				"t" : numberlong(1)
			},
			"optimedate" : isodate("2021-10-20t06:24:23z"),
			"syncsourcehost" : "",
			"syncsourceid" : -1,
			"infomessage" : "",
			"electiontime" : timestamp(1634710961, 1),
			"electiondate" : isodate("2021-10-20t06:22:41z"),
			"configversion" : 1,
			"configterm" : 1,
			"self" : true,
			"lastheartbeatmessage" : ""
		},
		{
			"_id" : 1,
			"name" : "10.0.0.57:27017",
			"health" : 1,
			"state" : 2,
			"statestr" : "secondary",
			"uptime" : 113,
			"optime" : {
				"ts" : timestamp(1634711061, 1),
				"t" : numberlong(1)
			},
			"optimedurable" : {
				"ts" : timestamp(1634711061, 1),
				"t" : numberlong(1)
			},
			"optimedate" : isodate("2021-10-20t06:24:21z"),
			"optimedurabledate" : isodate("2021-10-20t06:24:21z"),
			"lastheartbeat" : isodate("2021-10-20t06:24:22.487z"),
			"lastheartbeatrecv" : isodate("2021-10-20t06:24:22.906z"),
			"pingms" : numberlong(0),
			"lastheartbeatmessage" : "",
			"syncsourcehost" : "10.0.0.56:27017",
			"syncsourceid" : 0,
			"infomessage" : "",
			"configversion" : 1,
			"configterm" : 1
		},
		{
			"_id" : 2,
			"name" : "10.0.0.58:27017",
			"health" : 1,
			"state" : 2,
			"statestr" : "secondary",
			"uptime" : 113,
			"optime" : {
				"ts" : timestamp(1634711062, 1),
				"t" : numberlong(1)
			},
			"optimedurable" : {
				"ts" : timestamp(1634711062, 1),
				"t" : numberlong(1)
			},
			"optimedate" : isodate("2021-10-20t06:24:22z"),
			"optimedurabledate" : isodate("2021-10-20t06:24:22z"),
			"lastheartbeat" : isodate("2021-10-20t06:24:23.495z"),
			"lastheartbeatrecv" : isodate("2021-10-20t06:24:22.514z"),
			"pingms" : numberlong(0),
			"lastheartbeatmessage" : "",
			"syncsourcehost" : "10.0.0.56:27017",
			"syncsourceid" : 0,
			"infomessage" : "",
			"configversion" : 1,
			"configterm" : 1
		}
	],
	"ok" : 1,
	"$glestats" : {
		"lastoptime" : timestamp(1634710950, 1),
		"electionid" : objectid("7fffffff0000000000000001")
	},
	"lastcommittedoptime" : timestamp(1634711063, 1),
	"$clustertime" : {
		"clustertime" : timestamp(1634711063, 1),
		"signature" : {
			"hash" : bindata(0,"aaaaaaaaaaaaaaaaaaaaaaaaaaa="),
			"keyid" : numberlong(0)
		}
	},
	"operationtime" : timestamp(1634711063, 1)
}

5.配置部署shard1分片集群，启动shard1实例（三台执行同样操作）

cd /mongo/apps/conf
mongod --config mongo-shard1.yml

#查看端口40001是否启动
netstat -ntpl
active internet connections (only servers)
proto recv-q send-q local address           foreign address         state       pid/program name
tcp        0      0 0.0.0.0:40001           0.0.0.0:*               listen      5742/mongod
tcp        0      0 0.0.0.0:27017           0.0.0.0:*               listen      5443/mongod
tcp        0      0 0.0.0.0:111             0.0.0.0:*               listen      1/systemd
tcp        0      0 0.0.0.0:22              0.0.0.0:*               listen      1139/sshd
tcp        0      0 127.0.0.1:631           0.0.0.0:*               listen      1133/cupsd
tcp        0      0 127.0.0.1:6010          0.0.0.0:*               listen      2490/sshd: root@pts
tcp        0      0 127.0.0.1:6011          0.0.0.0:*               listen      5189/sshd: root@pts
tcp6       0      0 :::111                  :::*                    listen      1/systemd
tcp6       0      0 :::22                   :::*                    listen      1139/sshd
tcp6       0      0 ::1:631                 :::*                    listen      1133/cupsd
tcp6       0      0 ::1:6010                :::*                    listen      2490/sshd: root@pts
tcp6       0      0 ::1:6011                :::*                    listen      5189/sshd: root@pts

6.连接一台实例，创建复制集

#连接mongo
mongo 10.0.0.56:40001

#配置初始化复制集
config={_id:"shard1",members:[ 
  {_id:0,host:"10.0.0.56:40001",priority:2},
  {_id:1,host:"10.0.0.57:40001",priority:1},
  {_id:2,host:"10.0.0.58:40001",arbiteronly:true}, 
]}

rs.initiate(config)
#检查状态
rs.status()

7.配置部署shard2分片集群，启动shard1实例（三台执行同样操作）

cd /mongo/apps/conf
mongod --config mongo-shard2.yml

#查看端口40002是否启动
netstat -ntpl
active internet connections (only servers)
proto recv-q send-q local address           foreign address         state       pid/program name
tcp        0      0 0.0.0.0:40001           0.0.0.0:*               listen      5742/mongod
tcp        0      0 0.0.0.0:40002           0.0.0.0:*               listen      5982/mongod
tcp        0      0 0.0.0.0:27017           0.0.0.0:*               listen      5443/mongod
tcp        0      0 0.0.0.0:111             0.0.0.0:*               listen      1/systemd
tcp        0      0 0.0.0.0:22              0.0.0.0:*               listen      1139/sshd
tcp        0      0 127.0.0.1:631           0.0.0.0:*               listen      1133/cupsd
tcp        0      0 127.0.0.1:6010          0.0.0.0:*               listen      2490/sshd: root@pts
tcp        0      0 127.0.0.1:6011          0.0.0.0:*               listen      5189/sshd: root@pts
tcp6       0      0 :::111                  :::*                    listen      1/systemd
tcp6       0      0 :::22                   :::*                    listen      1139/sshd
tcp6       0      0 ::1:631                 :::*                    listen      1133/cupsd
tcp6       0      0 ::1:6010                :::*                    listen      2490/sshd: root@pts
tcp6       0      0 ::1:6011                :::*                    listen      5189/sshd: root@pts

8.连接第二个节点创建复制集
因为我们规划的shard2的主节点是10.0.0.57:40002，仲裁节点不能写数据，所以要连接10.0.0.57主机

#连接mongo
mongo 10.0.0.57:40002

#创建初始化复制集
config={_id:"shard2",members:[
  {_id:0,host:"10.0.0.56:40002",arbiteronly:true}, 
  {_id:1,host:"10.0.0.57:40002",priority:2}, 
  {_id:2,host:"10.0.0.58:40002",priority:1}, 
]}

rs.initiate(config)
#查看状态
rs.status()

9.配置部署shard3分片集群，启动shard3实例（三台执行同样操作）

cd /mongo/apps/conf/
mongod --config mongo-shard3.yml

##查看端口40003是否启动
netstat -ntpl
active internet connections (only servers)
proto recv-q send-q local address           foreign address         state       pid/program name
tcp        0      0 0.0.0.0:40001           0.0.0.0:*               listen      5742/mongod
tcp        0      0 0.0.0.0:40002           0.0.0.0:*               listen      5982/mongod
tcp        0      0 0.0.0.0:40003           0.0.0.0:*               listen      6454/mongod
tcp        0      0 0.0.0.0:27017           0.0.0.0:*               listen      5443/mongod
tcp        0      0 0.0.0.0:111             0.0.0.0:*               listen      1/systemd
tcp        0      0 0.0.0.0:22              0.0.0.0:*               listen      1139/sshd
tcp        0      0 127.0.0.1:631           0.0.0.0:*               listen      1133/cupsd
tcp        0      0 127.0.0.1:6010          0.0.0.0:*               listen      2490/sshd: root@pts
tcp        0      0 127.0.0.1:6011          0.0.0.0:*               listen      5189/sshd: root@pts
tcp6       0      0 :::111                  :::*                    listen      1/systemd
tcp6       0      0 :::22                   :::*                    listen      1139/sshd
tcp6       0      0 ::1:631                 :::*                    listen      1133/cupsd
tcp6       0      0 ::1:6010                :::*                    listen      2490/sshd: root@pts
tcp6       0      0 ::1:6011                :::*                    listen      5189/sshd: root@pts

10.连接第三个节点（10.0.0.58:40003）创建复制集

#连接mongo
mongo 10.0.0.58:40003

#创建初始化复制集
config={_id:"shard3",members:[ 
  {_id:0,host:"10.0.0.56:40003",priority:1}, 
  {_id:1,host:"10.0.0.57:40003",arbiteronly:true}, 
  {_id:2,host:"10.0.0.58:40003",priority:2}, 
]}

rs.initiate(config)
#查看状态
rs.status()

11.配置部署路由节点

#路由节点启动登录用mongos
mongos --config mongo-route.yml

#连接添加分片到集群中
mongo 10.0.0.56:30000

sh.addshard("shard1/10.0.0.56:40001,10.0.0.57:40001,10.0.0.58:40001")
sh.addshard("shard2/10.0.0.56:40002,10.0.0.57:40002,10.0.0.58:40002")
sh.addshard("shard3/10.0.0.56:40003,10.0.0.57:40003,10.0.0.58:40003")

#查看分片状态
sh.status()

四，测试服务器分片功能

#查看所有库
mongos> show dbs
admin   0.000gb
config  0.003gb
#进入config
use config
#这里默认的chunk大小是64m，db.settings.find()可以看到这个值，这里为了测试看的清楚，把chunk调整为1m
db.settings.save({"_id":"chunksize","value":1})

模拟写入数据

#在tydb库的tyuser表中循环写入6万条数据
mongos> use tydb
mongos> show tables
mongos> for(i=1;i<=60000;i++){db.tyuser.insert({"id":i,"name":"ty"+i})}

启用数据库分片

mongos> sh.enablesharding("tydb")
#ok返回1
{
	"ok" : 1,
	"operationtime" : timestamp(1634716737, 2),
	"$clustertime" : {
		"clustertime" : timestamp(1634716737, 2),
		"signature" : {
			"hash" : bindata(0,"aaaaaaaaaaaaaaaaaaaaaaaaaaa="),
			"keyid" : numberlong(0)
		}
	}
}

启用表分片

mongos> sh.shardcollection(”tydb.tyuser",{"id":1})

查看分片情况

mongos> sh.status()

查看开启关闭平衡器

#开启
mongos> sh.startbalancer() #或者sh.startbalancer(true)
#关闭
mongos> sh.stopbalancer() #或者sh.stopbalancer(false)
#查看是否关闭
mongos> sh.getbalancerstate() #返回flase表示关闭

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