MongoDB--副本集

时间 2020-11-30

标签 node shell 数据库 vim 数组 bash 服务器网络 app 异步栏目 MongoDB 繁體版

原文原文链接

MongoDB Replica Setsnode

简介

MongoDB中的副本集(Replica Set)是一组维护相同数据集的mongod服务。副本集可提供冗余和高可用性，是全部生产部署的基础。shell

也能够说，副本集相似于有自动故障修复功能的主从集群。通俗的讲就使用多台机器进行同一数据的异步同步，从而使多台机器拥有同一数据的多个副本，而且当主库宕机时再不须要用户干预的状况下自动切换其余备份服务器作主库。并且还能够利用副本服务器作只读服务器，实现读写分离，提升负载。数据库

1 冗余和数据可用性vim

复制提供冗余并提升数据可用性。经过在不一样数据库服务器上提供多个数据副本，复制可提供必定级别的容错功能，以防止丢失单个数据库服务器。数组

在某些状况下，复制能够提供增长的读取性能，由于客户端能够将读取操做发送到不一样的服务上，在不一样数据中心维护数据副本能够增长分布式应用程序的数据位置和可用性。bash

2 MongoDB中的复制服务器

副本集是一组维护相同数据集的mongod实例。副本集包含多个数据承载节点和可选的一个仲裁节点。在承载数据的节点中，一个且仅一个成员视为主节点，而其余节点被视为要（从）节点。网络

主节点接收全部的操做。副本集只能有一个主要可以确认具备{w:"most"}写入关注的写入；虽然在某些状况下，另外一个mongod实例可能暂时认为本身也是主要的。主要记录其操做日志中的数据集的全部更改，即oplog。app

3 主从复制和副本集区别异步

主从集群和副本集最大的区别就是副本集没有固定的“主节点”；整个集群会选出一个“主节点”，当其挂掉后，又在剩下的从节点中选中其余节点为“主节点”，副本集总有一个活跃点（主、primary）和一个或多个备份节点（从、secondary）

副本集的三个角色

副本集有两种类型三种角色

两种类型：

主节点（Primary）类型：数据操做的主要链接带你，可读写。

次要（辅助、从）节点（Secondaries）类型：数据冗余备份节点，能够读或选举。

三种角色：

主要成员（Primary）：主要接收全部写操做。就是主节点。

副本成员（Replicate）：从节点经过复制操做以维护相同的数据集，即备份数据，不可泄操做，但能够读操做（但须要配置）。是默认的一种从节点类型。

仲裁者（Arbiter）：不保留任何数据的副本，只具备投票选举做用。固然也能够将仲裁服务器维护为副本集的一部分，即副本成员同事也能够是仲裁者。也是一种从节点类型。

搭建副本集集群

一主一副本一仲裁

这里在一台机器上面进行搭建，经过多端口方式实现

建立主节点

1.建立数据存储和日志存放目录

# mkdir -p /data/replica_sets/myrs_27017/log
# mkdir -p /data/replica_sets/myrs_27017/data/db

2.新建或修改配置文件

# vim /data/replica_sets/myrs_27017/mongod.conf 
systemLog:
    #日志输出的目标指定为文件
    destination: file
    #日志存放目录
    path: "/data/replica_sets/myrs_27017/log/mongod.log"
    #当mongos或mongod实例从新启动时，mongos或mongod会将新条目附加到现有日志文件的末尾
    logAppend: true
storage:
    #mongod实例存储其数据的目录
    dbPath: "/data/replica_sets/myrs_27017/data/db"
    journal:
        #启用或禁用持久性日志已确保数据文件保持有效和可恢复 
        enabled: true
processManagement:
    #启用在后台运行mongos或mongod进程的守护进程模式
    fork: true
    #指定用于保存mongos或mongod进程的进程ID的文件位置
    pidFilePath: "/data/replica_sets/myrs_27017/log/mongod.pid"
net:
    #服务实例绑定IP
    bindIp: 127.0.0.1,10.10.10.11
    #服务实例绑定端口
    port: 27017
replication:
    #副本集的名称
    replSetName: myrs

3.启动节点服务

# mongod -f /data/replica_sets/myrs_27017/mongod.conf 
about to fork child process, waiting until server is ready for connections.
forked process: 23945
child process started successfully, parent exiting

建立副本节点

1.建立数据存储和日志存放目录

# mkdir -p /data/replica_sets/myrs_27018/log
# mkdir -p /data/replica_sets/myrs_27018/data/db

2.新建或修改配置文件

# vim /data/replica_sets/myrs_27018/mongod.conf 
systemLog:
    #日志输出的目标指定为文件
    destination: file
    #日志存放目录
    path: "/data/replica_sets/myrs_27018/log/mongod.log"
    #当mongos或mongod实例从新启动时，mongos或mongod会将新条目附加到现有日志文件的末尾
    logAppend: true
storage:
    #mongod实例存储其数据的目录
    dbPath: "/data/replica_sets/myrs_27018/data/db"
    journal:
        #启用或禁用持久性日志已确保数据文件保持有效和可恢复 
        enabled: true
processManagement:
    #启用在后台运行mongos或mongod进程的守护进程模式
    fork: true
    #指定用于保存mongos或mongod进程的进程ID的文件位置
    pidFilePath: "/data/replica_sets/myrs_27018/log/mongod.pid"
net:
    #服务实例绑定IP
    bindIp: 127.0.0.1,10.10.10.11
    #服务实例绑定端口
    port: 27018
replication:
    #副本集的名称
    replSetName: myrs

3.启动节点服务

# mongod -f /data/replica_sets/myrs_27018/mongod.conf 
about to fork child process, waiting until server is ready for connections.
forked process: 24174
child process started successfully, parent exiting

建立仲裁节点

1.建立数据存储和日志存放目录

# mkdir -p /data/replica_sets/myrs_27019/log
# mkdir -p /data/replica_sets/myrs_27019/data/db

2.新建或修改配置文件

# vim /data/replica_sets/myrs_27019/mongod.conf
systemLog:
    #日志输出的目标指定为文件
    destination: file
    #日志存放目录
    path: "/data/replica_sets/myrs_27019/log/mongod.log"
    #当mongos或mongod实例从新启动时，mongos或mongod会将新条目附加到现有日志文件的末尾
    logAppend: true
storage:
    #mongod实例存储其数据的目录
    dbPath: "/data/replica_sets/myrs_27019/data/db"
    journal:
        #启用或禁用持久性日志已确保数据文件保持有效和可恢复 
        enabled: true
processManagement:
    #启用在后台运行mongos或mongod进程的守护进程模式
    fork: true
    #指定用于保存mongos或mongod进程的进程ID的文件位置
    pidFilePath: "/data/replica_sets/myrs_27019/log/mongod.pid"
net:
    #服务实例绑定IP
    bindIp: 127.0.0.1,10.10.10.11
    #服务实例绑定端口
    port: 27019
replication:
    #副本集的名称
    replSetName: myrs

3.启动节点服务

# mongod -f /data/replica_sets/myrs_27019/mongod.conf 
about to fork child process, waiting until server is ready for connections.
forked process: 24441
child process started successfully, parent exiting

初始化配置副本集

1.使用客户端命令链接任意一个节点，初始化主节点（这里选择27017）

# mongo --host=10.10.10.11 --port=27017

备注：链接上以后，不少命令没法使用，好比show dbs等，必须初始化副本集才行

2.初始化新的副本集（命令：rs.initiate()）

> rs.initiate()
{
	"info2" : "no configuration specified. Using a default configuration for the set",
	"me" : "10.10.10.11:27017",
	"ok" : 1,
	"$clusterTime" : {
		"clusterTime" : Timestamp(1604913568, 1),
		"signature" : {
			"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
			"keyId" : NumberLong(0)
		}
	},
	"operationTime" : Timestamp(1604913568, 1)
}
myrs:SECONDARY> 
myrs:PRIMARY>

备注：

1）"ok"的值为1，说明建立成功。

2）命令行提示符发生变化，变成了一个从节点角色，此时默认不能读写。稍等片刻，回车，变成主节点。

查看副本集的配置

返回包含当前副本集配置的文档。

语法：rs.conf(configuration)

备注：

rs.config()是该方法的别名。

configuration：可选，若是没有配置，则使用默认主节点配置。

示例：在27017上执行副本集中当前节点的默认节点配置

myrs:PRIMARY> rs.conf()
{
	"_id" : "myrs",
	"version" : 1,
	"term" : 1,
	"protocolVersion" : NumberLong(1),
	"writeConcernMajorityJournalDefault" : true,
	"members" : [
		{
			"_id" : 0,
			"host" : "10.10.10.11:27017",
			"arbiterOnly" : false,
			"buildIndexes" : true,
			"hidden" : false,
			"priority" : 1,
			"tags" : {
				
			},
			"slaveDelay" : NumberLong(0),
			"votes" : 1
		}
	],
	"settings" : {
		"chainingAllowed" : true,
		"heartbeatIntervalMillis" : 2000,
		"heartbeatTimeoutSecs" : 10,
		"electionTimeoutMillis" : 10000,
		"catchUpTimeoutMillis" : -1,
		"catchUpTakeoverDelayMillis" : 30000,
		"getLastErrorModes" : {
			
		},
		"getLastErrorDefaults" : {
			"w" : 1,
			"wtimeout" : 0
		},
		"replicaSetId" : ObjectId("5fa909a07e34d2b6fa2e54a1")
	}
}

说明：

1）"_id" : "myrs"：副本集的配置数据存储的主键值，默认就是副本集的名字

2）"members"：副本集成员数组，此时只有一个："host" : "10.10.10.11:27017"，该成员不是仲裁节点："arbiterOnly" : false，优先级（权重值）："priority" : 1，

3）"settings"：副本集的参数配置

提示：副本集配置的查看命令，本质是查询的是system.replset的表中的数据：

myrs:PRIMARY> use local
switched to db local
myrs:PRIMARY> show collections
oplog.rs
replset.election
replset.initialSyncId
replset.minvalid
replset.oplogTruncateAfterPoint
startup_log
system.replset
system.rollback.id
myrs:PRIMARY> db.system.replset.find()
{ "_id" : "myrs", "version" : 1, "term" : 1, "protocolVersion" : NumberLong(1), "writeConcernMajorityJournalDefault" : true, "members" : [ { "_id" : 0, "host" : "10.10.10.11:27017", "arbiterOnly" : false, "buildIndexes" : true, "hidden" : false, "priority" : 1, "tags" : {  }, "slaveDelay" : NumberLong(0), "votes" : 1 } ], "settings" : { "chainingAllowed" : true, "heartbeatIntervalMillis" : 2000, "heartbeatTimeoutSecs" : 10, "electionTimeoutMillis" : 10000, "catchUpTimeoutMillis" : -1, "catchUpTakeoverDelayMillis" : 30000, "getLastErrorModes" : {  }, "getLastErrorDefaults" : { "w" : 1, "wtimeout" : 0 }, "replicaSetId" : ObjectId("5fa909a07e34d2b6fa2e54a1") } }

查看副本集的状态

说明：返回包含状态信息的文档，次输出结果从副本集的其余成员发送的心跳包中得到的数据反映副本集的当前状态

语法：rs.status()

在27017上查看副本集状态

myrs:PRIMARY> rs.status()
{
	"set" : "myrs",
	"date" : ISODate("2020-11-10T01:15:18.661Z"),
	"myState" : 1,
	"term" : NumberLong(1),
	"syncSourceHost" : "",
	"syncSourceId" : -1,
	"heartbeatIntervalMillis" : NumberLong(2000),
	"majorityVoteCount" : 1,
	"writeMajorityCount" : 1,
	"votingMembersCount" : 1,
	"writableVotingMembersCount" : 1,
	"optimes" : {
		"lastCommittedOpTime" : {
			"ts" : Timestamp(1604970915, 1),
			"t" : NumberLong(1)
		},
		"lastCommittedWallTime" : ISODate("2020-11-10T01:15:15.402Z"),
		"readConcernMajorityOpTime" : {
			"ts" : Timestamp(1604970915, 1),
			"t" : NumberLong(1)
		},
		"readConcernMajorityWallTime" : ISODate("2020-11-10T01:15:15.402Z"),
		"appliedOpTime" : {
			"ts" : Timestamp(1604970915, 1),
			"t" : NumberLong(1)
		},
		"durableOpTime" : {
			"ts" : Timestamp(1604970915, 1),
			"t" : NumberLong(1)
		},
		"lastAppliedWallTime" : ISODate("2020-11-10T01:15:15.402Z"),
		"lastDurableWallTime" : ISODate("2020-11-10T01:15:15.402Z")
	},
	"lastStableRecoveryTimestamp" : Timestamp(1604970895, 1),
	"electionCandidateMetrics" : {
		"lastElectionReason" : "electionTimeout",
		"lastElectionDate" : ISODate("2020-11-09T09:19:28.377Z"),
		"electionTerm" : NumberLong(1),
		"lastCommittedOpTimeAtElection" : {
			"ts" : Timestamp(0, 0),
			"t" : NumberLong(-1)
		},
		"lastSeenOpTimeAtElection" : {
			"ts" : Timestamp(1604913568, 1),
			"t" : NumberLong(-1)
		},
		"numVotesNeeded" : 1,
		"priorityAtElection" : 1,
		"electionTimeoutMillis" : NumberLong(10000),
		"newTermStartDate" : ISODate("2020-11-09T09:19:28.401Z"),
		"wMajorityWriteAvailabilityDate" : ISODate("2020-11-09T09:19:28.420Z")
	},
	"members" : [
		{
			"_id" : 0,
			"name" : "10.10.10.11:27017",
			"health" : 1,
			"state" : 1,
			"stateStr" : "PRIMARY",
			"uptime" : 57734,
			"optime" : {
				"ts" : Timestamp(1604970915, 1),
				"t" : NumberLong(1)
			},
			"optimeDate" : ISODate("2020-11-10T01:15:15Z"),
			"syncSourceHost" : "",
			"syncSourceId" : -1,
			"infoMessage" : "",
			"electionTime" : Timestamp(1604913568, 2),
			"electionDate" : ISODate("2020-11-09T09:19:28Z"),
			"configVersion" : 1,
			"configTerm" : 1,
			"self" : true,
			"lastHeartbeatMessage" : ""
		}
	],
	"ok" : 1,
	"$clusterTime" : {
		"clusterTime" : Timestamp(1604970915, 1),
		"signature" : {
			"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
			"keyId" : NumberLong(0)
		}
	},
	"operationTime" : Timestamp(1604970915, 1)
}

说明：

1）"set" : "myrs"：副本集的名字

2）"myState" : 1：说明状态正常

3）"members"：副本集成员数组，此时只有一个："name" : "10.10.10.11:27017"，该成员的角色是"stateStr" : "PRIMARY"，该节点是健康的："health" : 1。

添加副本从节点

在主节点添加从节点，将其余成员加入到副本集

语法：

rs.add(host, arbiterOnly)

Parameter	Type	Description
`host`	string or document	要添加到副本集的新成员。指定为字符串或配置文档：1）若是是一个字符串，则须要指定新成员的主机名和可选的端口；2）若是是一个文档，须要指定在members数组中找到的副本集成员配置文档。必须在成员配置文档中指定主机字段。详见下方文档：“主机成员的配置文档”
`arbiterOnly`	boolean	可选的。仅在值为字符串时使用。若是为true，则添加的主机是仲裁者。

主机成员的配置文档：

{ 
	_id: <int>, 
	host: <string>, // required 
	arbiterOnly: <boolean>, 
	buildIndexes: <boolean>, 
	hidden: <boolean>, 
	priority: <number>, 
	tags: <document>, 
	slaveDelay: <int>, 
	votes: <number> 
}

将27018的副本节点添加到副本集中：

myrs:PRIMARY> rs.add("10.10.10.11:27018")
{
	"ok" : 1,
	"$clusterTime" : {
		"clusterTime" : Timestamp(1604975516, 1),
		"signature" : {
			"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
			"keyId" : NumberLong(0)
		}
	},
	"operationTime" : Timestamp(1604975516, 1)
}

说明：

1）"ok" : 1：说明添加成功。

查看副本集状态

myrs:PRIMARY> rs.status()
{
	"set" : "myrs",
	"date" : ISODate("2020-11-10T02:33:54.698Z"),
	"myState" : 1,
	"term" : NumberLong(1),
	"syncSourceHost" : "",
	"syncSourceId" : -1,
	"heartbeatIntervalMillis" : NumberLong(2000),
	"majorityVoteCount" : 2,
	"writeMajorityCount" : 2,
	"votingMembersCount" : 2,
	"writableVotingMembersCount" : 2,
	"optimes" : {
		"lastCommittedOpTime" : {
			"ts" : Timestamp(1604975625, 1),
			"t" : NumberLong(1)
		},
		"lastCommittedWallTime" : ISODate("2020-11-10T02:33:45.868Z"),
		"readConcernMajorityOpTime" : {
			"ts" : Timestamp(1604975625, 1),
			"t" : NumberLong(1)
		},
		"readConcernMajorityWallTime" : ISODate("2020-11-10T02:33:45.868Z"),
		"appliedOpTime" : {
			"ts" : Timestamp(1604975625, 1),
			"t" : NumberLong(1)
		},
		"durableOpTime" : {
			"ts" : Timestamp(1604975625, 1),
			"t" : NumberLong(1)
		},
		"lastAppliedWallTime" : ISODate("2020-11-10T02:33:45.868Z"),
		"lastDurableWallTime" : ISODate("2020-11-10T02:33:45.868Z")
	},
	"lastStableRecoveryTimestamp" : Timestamp(1604975575, 1),
	"electionCandidateMetrics" : {
		"lastElectionReason" : "electionTimeout",
		"lastElectionDate" : ISODate("2020-11-09T09:19:28.377Z"),
		"electionTerm" : NumberLong(1),
		"lastCommittedOpTimeAtElection" : {
			"ts" : Timestamp(0, 0),
			"t" : NumberLong(-1)
		},
		"lastSeenOpTimeAtElection" : {
			"ts" : Timestamp(1604913568, 1),
			"t" : NumberLong(-1)
		},
		"numVotesNeeded" : 1,
		"priorityAtElection" : 1,
		"electionTimeoutMillis" : NumberLong(10000),
		"newTermStartDate" : ISODate("2020-11-09T09:19:28.401Z"),
		"wMajorityWriteAvailabilityDate" : ISODate("2020-11-09T09:19:28.420Z")
	},
	"members" : [
		{
			"_id" : 0,
			"name" : "10.10.10.11:27017",
			"health" : 1,
			"state" : 1,
			"stateStr" : "PRIMARY",
			"uptime" : 62450,
			"optime" : {
				"ts" : Timestamp(1604975625, 1),
				"t" : NumberLong(1)
			},
			"optimeDate" : ISODate("2020-11-10T02:33:45Z"),
			"syncSourceHost" : "",
			"syncSourceId" : -1,
			"infoMessage" : "",
			"electionTime" : Timestamp(1604913568, 2),
			"electionDate" : ISODate("2020-11-09T09:19:28Z"),
			"configVersion" : 2,
			"configTerm" : 1,
			"self" : true,
			"lastHeartbeatMessage" : ""
		},
		{
			"_id" : 1,
			"name" : "10.10.10.11:27018",
			"health" : 1,
			"state" : 2,
			"stateStr" : "SECONDARY",
			"uptime" : 117,
			"optime" : {
				"ts" : Timestamp(1604975625, 1),
				"t" : NumberLong(1)
			},
			"optimeDurable" : {
				"ts" : Timestamp(1604975625, 1),
				"t" : NumberLong(1)
			},
			"optimeDate" : ISODate("2020-11-10T02:33:45Z"),
			"optimeDurableDate" : ISODate("2020-11-10T02:33:45Z"),
			"lastHeartbeat" : ISODate("2020-11-10T02:33:52.778Z"),
			"lastHeartbeatRecv" : ISODate("2020-11-10T02:33:53.089Z"),
			"pingMs" : NumberLong(0),
			"lastHeartbeatMessage" : "",
			"syncSourceHost" : "10.10.10.11:27017",
			"syncSourceId" : 0,
			"infoMessage" : "",
			"configVersion" : 2,
			"configTerm" : 1
		}
	],
	"ok" : 1,
	"$clusterTime" : {
		"clusterTime" : Timestamp(1604975625, 1),
		"signature" : {
			"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
			"keyId" : NumberLong(0)
		}
	},
	"operationTime" : Timestamp(1604975625, 1)
}

说明：

1）"name" : "10.10.10.11:27018"是第二个节点的名字，其角色是"stateStr" : "SECONDARY"

添加仲裁节点

在主节点添加一个仲裁节点到副本集

语法：

rs.addArb(host)

将27019节点添加到副本集中做为仲裁节点：

myrs:PRIMARY> rs.addArb("10.10.10.11:27019")
{
	"ok" : 1,
	"$clusterTime" : {
		"clusterTime" : Timestamp(1604989664, 1),
		"signature" : {
			"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
			"keyId" : NumberLong(0)
		}
	},
	"operationTime" : Timestamp(1604989664, 1)
}

说明：

1）"ok" : 1：说明添加成功

查看副本集状态：

myrs:PRIMARY> rs.status()
{
	"set" : "myrs",
	"date" : ISODate("2020-11-10T06:28:31.102Z"),
	"myState" : 1,
	"term" : NumberLong(1),
	"syncSourceHost" : "",
	"syncSourceId" : -1,
	"heartbeatIntervalMillis" : NumberLong(2000),
	"majorityVoteCount" : 2,
	"writeMajorityCount" : 2,
	"votingMembersCount" : 3,
	"writableVotingMembersCount" : 2,
	"optimes" : {
		"lastCommittedOpTime" : {
			"ts" : Timestamp(1604989707, 1),
			"t" : NumberLong(1)
		},
		"lastCommittedWallTime" : ISODate("2020-11-10T06:28:27.292Z"),
		"readConcernMajorityOpTime" : {
			"ts" : Timestamp(1604989707, 1),
			"t" : NumberLong(1)
		},
		"readConcernMajorityWallTime" : ISODate("2020-11-10T06:28:27.292Z"),
		"appliedOpTime" : {
			"ts" : Timestamp(1604989707, 1),
			"t" : NumberLong(1)
		},
		"durableOpTime" : {
			"ts" : Timestamp(1604989707, 1),
			"t" : NumberLong(1)
		},
		"lastAppliedWallTime" : ISODate("2020-11-10T06:28:27.292Z"),
		"lastDurableWallTime" : ISODate("2020-11-10T06:28:27.292Z")
	},
	"lastStableRecoveryTimestamp" : Timestamp(1604989675, 1),
	"electionCandidateMetrics" : {
		"lastElectionReason" : "electionTimeout",
		"lastElectionDate" : ISODate("2020-11-09T09:19:28.377Z"),
		"electionTerm" : NumberLong(1),
		"lastCommittedOpTimeAtElection" : {
			"ts" : Timestamp(0, 0),
			"t" : NumberLong(-1)
		},
		"lastSeenOpTimeAtElection" : {
			"ts" : Timestamp(1604913568, 1),
			"t" : NumberLong(-1)
		},
		"numVotesNeeded" : 1,
		"priorityAtElection" : 1,
		"electionTimeoutMillis" : NumberLong(10000),
		"newTermStartDate" : ISODate("2020-11-09T09:19:28.401Z"),
		"wMajorityWriteAvailabilityDate" : ISODate("2020-11-09T09:19:28.420Z")
	},
	"members" : [
		{
			"_id" : 0,
			"name" : "10.10.10.11:27017",
			"health" : 1,
			"state" : 1,
			"stateStr" : "PRIMARY",
			"uptime" : 76527,
			"optime" : {
				"ts" : Timestamp(1604989707, 1),
				"t" : NumberLong(1)
			},
			"optimeDate" : ISODate("2020-11-10T06:28:27Z"),
			"syncSourceHost" : "",
			"syncSourceId" : -1,
			"infoMessage" : "",
			"electionTime" : Timestamp(1604913568, 2),
			"electionDate" : ISODate("2020-11-09T09:19:28Z"),
			"configVersion" : 3,
			"configTerm" : 1,
			"self" : true,
			"lastHeartbeatMessage" : ""
		},
		{
			"_id" : 1,
			"name" : "10.10.10.11:27018",
			"health" : 1,
			"state" : 2,
			"stateStr" : "SECONDARY",
			"uptime" : 14194,
			"optime" : {
				"ts" : Timestamp(1604989707, 1),
				"t" : NumberLong(1)
			},
			"optimeDurable" : {
				"ts" : Timestamp(1604989707, 1),
				"t" : NumberLong(1)
			},
			"optimeDate" : ISODate("2020-11-10T06:28:27Z"),
			"optimeDurableDate" : ISODate("2020-11-10T06:28:27Z"),
			"lastHeartbeat" : ISODate("2020-11-10T06:28:30.884Z"),
			"lastHeartbeatRecv" : ISODate("2020-11-10T06:28:30.897Z"),
			"pingMs" : NumberLong(0),
			"lastHeartbeatMessage" : "",
			"syncSourceHost" : "10.10.10.11:27017",
			"syncSourceId" : 0,
			"infoMessage" : "",
			"configVersion" : 3,
			"configTerm" : 1
		},
		{
			"_id" : 2,
			"name" : "10.10.10.11:27019",
			"health" : 1,
			"state" : 7,
			"stateStr" : "ARBITER",
			"uptime" : 46,
			"lastHeartbeat" : ISODate("2020-11-10T06:28:30.900Z"),
			"lastHeartbeatRecv" : ISODate("2020-11-10T06:28:30.917Z"),
			"pingMs" : NumberLong(0),
			"lastHeartbeatMessage" : "",
			"syncSourceHost" : "",
			"syncSourceId" : -1,
			"infoMessage" : "",
			"configVersion" : 3,
			"configTerm" : 1
		}
	],
	"ok" : 1,
	"$clusterTime" : {
		"clusterTime" : Timestamp(1604989707, 1),
		"signature" : {
			"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
			"keyId" : NumberLong(0)
		}
	},
	"operationTime" : Timestamp(1604989707, 1)
}

说明：

1）"name" : "10.10.10.11:27019"是第二个节点的名字，其角色是"stateStr" : "ARBITER"

副本集的数据读写操做

测试三个不一样角色的节点的数据读写状况。

一、测试主节点27017，写入和读数据：

# mongo --host=10.10.10.11 --port=27017
myrs:PRIMARY> use collectest
switched to db collectest
myrs:PRIMARY> db
collectest
myrs:PRIMARY> db.collectest.insert({"name":"张三","sex":"男","age":22,"userid":1001,"createdatetime":new Date()})
WriteResult({ "nInserted" : 1 })
myrs:PRIMARY> 
myrs:PRIMARY> db.collectest.find()
{ "_id" : ObjectId("5faa3432f6e79c62c00e4d72"), "name" : "张三", "sex" : "男", "age" : 22, "userid" : 1001, "createdatetime" : ISODate("2020-11-10T06:33:22.459Z") }
myrs:PRIMARY>

说明：经过测试能够发现主节点是能够进行数据的读和写操做的。

二、测试从节点

# mongo --host=10.10.10.11 --port=27018
myrs:SECONDARY> show dbs
uncaught exception: Error: listDatabases failed:{
	"topologyVersion" : {
		"processId" : ObjectId("5fa909804c7cb6020458ce77"),
		"counter" : NumberLong(5)
	},
	"operationTime" : Timestamp(1605085202, 1),
	"ok" : 0,
	"errmsg" : "not master and slaveOk=false",
	"code" : 13435,
	"codeName" : "NotMasterNoSlaveOk",
	"$clusterTime" : {
		"clusterTime" : Timestamp(1605085202, 1),
		"signature" : {
			"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
			"keyId" : NumberLong(0)
		}
	}
} :
_getErrorWithCode@src/mongo/shell/utils.js:25:13
Mongo.prototype.getDBs/<@src/mongo/shell/mongo.js:147:19
Mongo.prototype.getDBs@src/mongo/shell/mongo.js:99:12
shellHelper.show@src/mongo/shell/utils.js:937:13
shellHelper@src/mongo/shell/utils.js:819:15
@(shellhelp2):1:1

测试发现，不能读取集合的数据。当前从节点只是一个备份，不是奴隶节点，没法读取数据，写固然更不行。由于默认状况下，从节点是没有读写权限的，能够增长读的权限，可是须要进行设置。

设置读操做权限：

rs.secondaryOk()
#或者
rs.secondaryOk(true)

示例，在27018上面设置从节点具有读权限：

myrs:SECONDARY> rs.secondaryOk()
myrs:SECONDARY> show dbs
admin       0.000GB
collectest  0.000GB
config      0.000GB
local       0.000GB
myrs:SECONDARY> use collectest
switched to db collectest
myrs:SECONDARY> show collections
collectest
myrs:SECONDARY> 
myrs:SECONDARY> db.collectest.find()
{ "_id" : ObjectId("5faa3432f6e79c62c00e4d72"), "name" : "张三", "sex" : "男", "age" : 22, "userid" : 1001, "createdatetime" : ISODate("2020-11-10T06:33:22.459Z") }

这里便实现了读写分离，让主节点插入数据，让历来读取数据。

若是要取消从节点的读权限：

myrs:SECONDARY> rs.secondaryOk(false)
myrs:SECONDARY> show dbs
uncaught exception: Error: listDatabases failed:{
	"topologyVersion" : {
		"processId" : ObjectId("5fa909804c7cb6020458ce77"),
		"counter" : NumberLong(5)
	},
	"operationTime" : Timestamp(1605086322, 1),
	"ok" : 0,
	"errmsg" : "not master and slaveOk=false",
	"code" : 13435,
	"codeName" : "NotMasterNoSlaveOk",
	"$clusterTime" : {
		"clusterTime" : Timestamp(1605086322, 1),
		"signature" : {
			"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
			"keyId" : NumberLong(0)
		}
	}
} :
_getErrorWithCode@src/mongo/shell/utils.js:25:13
Mongo.prototype.getDBs/<@src/mongo/shell/mongo.js:147:19
Mongo.prototype.getDBs@src/mongo/shell/mongo.js:99:12
shellHelper.show@src/mongo/shell/utils.js:937:13
shellHelper@src/mongo/shell/utils.js:819:15
@(shellhelp2):1:1

三、测试仲裁节点，仲裁节点不会听任何业务数据，能够登录查看

# mongo --host=10.10.10.11 --port=27019
myrs:ARBITER> show dbs
uncaught exception: Error: listDatabases failed:{
	"topologyVersion" : {
		"processId" : ObjectId("5fa90b59bea51b269ba3eb82"),
		"counter" : NumberLong(3)
	},
	"ok" : 0,
	"errmsg" : "node is not in primary or recovering state",
	"code" : 13436,
	"codeName" : "NotMasterOrSecondary"
} :
_getErrorWithCode@src/mongo/shell/utils.js:25:13
Mongo.prototype.getDBs/<@src/mongo/shell/mongo.js:147:19
Mongo.prototype.getDBs@src/mongo/shell/mongo.js:99:12
shellHelper.show@src/mongo/shell/utils.js:937:13
shellHelper@src/mongo/shell/utils.js:819:15
@(shellhelp2):1:1

测试发现，仲裁节点不能进行数据的查看。

主节点的选举原则

MongoDB在副本集中，会自动进行主节点的选举，主节点选举的触发条件：

1）主节点故障

2）主节点网络不可达（默认心跳信息为10秒）

3）人工干预（rs.stepDown(600)）

一旦触发选举，就要根据必定规则来选主节点。

选举规则是根据票数来决定谁获胜：

票数最高，且得到了“大多数”成员的投票支持的节点获胜

若票数相同，且都得到了“大多数”成员的投票支持的，数据新的节点获胜。数据的新旧是经过操做日志oplog来对比的。

在得到票数的时候，优先级（priority）参数影响重大。能够经过设置优先级（priority）来设置额外票数。优先级即权重，取值为0-1000，至关于可额外增长0-1000的票数，优先级的值越大，就越有可能得到多数成员的投票（votes）数。指定较高的值可以使成员更有资格成为主要成员，更低的值可以使成员更不符合条件。

默认状况下，优先级都为1

myrs:SECONDARY> rs.conf()
{
	"_id" : "myrs",
	"version" : 3,
	"term" : 3,
	"protocolVersion" : NumberLong(1),
	"writeConcernMajorityJournalDefault" : true,
	"members" : [
		{
			"_id" : 0,
			"host" : "10.10.10.11:27017",
			"arbiterOnly" : false,
			"buildIndexes" : true,
			"hidden" : false,
			"priority" : 1,
			"tags" : {
				
			},
			"slaveDelay" : NumberLong(0),
			"votes" : 1
		},
		{
			"_id" : 1,
			"host" : "10.10.10.11:27018",
			"arbiterOnly" : false,
			"buildIndexes" : true,
			"hidden" : false,
			"priority" : 1,
			"tags" : {
				
			},
			"slaveDelay" : NumberLong(0),
			"votes" : 1
		},
		{
			"_id" : 2,
			"host" : "10.10.10.11:27019",
			"arbiterOnly" : true,
			"buildIndexes" : true,
			"hidden" : false,
			"priority" : 0,
			"tags" : {
				
			},
			"slaveDelay" : NumberLong(0),
			"votes" : 1
		}
	],
	"settings" : {
		"chainingAllowed" : true,
		"heartbeatIntervalMillis" : 2000,
		"heartbeatTimeoutSecs" : 10,
		"electionTimeoutMillis" : 10000,
		"catchUpTimeoutMillis" : -1,
		"catchUpTakeoverDelayMillis" : 30000,
		"getLastErrorModes" : {
			
		},
		"getLastErrorDefaults" : {
			"w" : 1,
			"wtimeout" : 0
		},
		"replicaSetId" : ObjectId("5fa909a07e34d2b6fa2e54a1")
	}
}

能够经过上面的配置信息看出，主节点和副本节点的优先级各位1，即，默承认以认为都已经有了一票。单选举节点，优先级是0，（注意：官方说了，选举节点的优先级必须是0，不能是别的值。即不具有选举权，单具备投票权）

故障测试

副本节点故障测试

关闭27018副本节点：

# ps -ef |grep mongo
root      23945      1  0 Nov10 ?        00:22:10 mongod -f /data/replica_sets/myrs_27017/mongod.conf
root      24174      1  0 Nov10 ?        00:22:33 mongod -f /data/replica_sets/myrs_27018/mongod.conf
root      24441      1  0 Nov10 ?        00:15:15 mongod -f /data/replica_sets/myrs_27019/mongod.conf
# kill -2 24174

进入主节点27017写入数据

# mongo --host=10.10.10.11 --port=27017
---
myrs:PRIMARY> use collectest
switched to db collectest
myrs:PRIMARY> db.collectest.insert({"name":"小白", "sex":"女", "age":20, "userid":1002, "createdatetime":new Date()})
WriteResult({ "nInserted" : 1 })

启动27018副本节点，并验证数据

# mongod -f /data/replica_sets/myrs_27018/mongod.conf
# mongo --host=10.10.10.11 --port=27018
myrs:SECONDARY> rs.secondaryOk()
myrs:SECONDARY> show dbs
admin       0.000GB
collectest  0.000GB
config      0.000GB
local       0.001GB
myrs:SECONDARY> use collectest
switched to db collectest
myrs:SECONDARY> db.collectest.find()
{ "_id" : ObjectId("5faa3432f6e79c62c00e4d72"), "name" : "张三", "sex" : "男", "age" : 22, "userid" : 1001, "createdatetime" : ISODate("2020-11-10T06:33:22.459Z") }
{ "_id" : ObjectId("5facec10cca53c48154d261c"), "name" : "小白", "sex" : "女", "age" : 20, "userid" : 1002, "createdatetime" : ISODate("2020-11-12T08:02:24.915Z") }

经过上面的测试验证，能够发现，当副本节点故障时，主节点读写不受影响，而且在副本节点恢复后，主节点写入的数据，会自动同步给从节点。

主节点故障测试

关闭主节点27017

# ps -ef |grep mongo
root      23945      1  0 Nov10 ?        00:22:34 mongod -f /data/replica_sets/myrs_27017/mongod.conf
root      24441      1  0 Nov10 ?        00:15:27 mongod -f /data/replica_sets/myrs_27019/mongod.conf
root      50521      1  1 16:04 ?        00:00:16 mongod -f /data/replica_sets/myrs_27018/mongod.conf
# kill -2 23945

登录副本节点查看集群状态

# mongo --host=10.10.10.11 --port=27018
myrs:PRIMARY> 
myrs:PRIMARY> rs.status()
{
	"set" : "myrs",
	"date" : ISODate("2020-11-12T08:30:11.791Z"),
	"myState" : 1,
	"term" : NumberLong(7),
	"syncSourceHost" : "",
	"syncSourceId" : -1,
	"heartbeatIntervalMillis" : NumberLong(2000),
	"majorityVoteCount" : 2,
	"writeMajorityCount" : 2,
	"votingMembersCount" : 3,
	"writableVotingMembersCount" : 2,
	"optimes" : {
		"lastCommittedOpTime" : {
			"ts" : Timestamp(1605169711, 1),
			"t" : NumberLong(5)
		},
		"lastCommittedWallTime" : ISODate("2020-11-12T08:28:31.364Z"),
		"readConcernMajorityOpTime" : {
			"ts" : Timestamp(1605169711, 1),
			"t" : NumberLong(5)
		},
		"readConcernMajorityWallTime" : ISODate("2020-11-12T08:28:31.364Z"),
		"appliedOpTime" : {
			"ts" : Timestamp(1605169802, 1),
			"t" : NumberLong(7)
		},
		"durableOpTime" : {
			"ts" : Timestamp(1605169802, 1),
			"t" : NumberLong(7)
		},
		"lastAppliedWallTime" : ISODate("2020-11-12T08:30:02.141Z"),
		"lastDurableWallTime" : ISODate("2020-11-12T08:30:02.141Z")
	},
	"lastStableRecoveryTimestamp" : Timestamp(1605169711, 1),
	"electionCandidateMetrics" : {
		"lastElectionReason" : "electionTimeout",
		"lastElectionDate" : ISODate("2020-11-12T08:28:42.106Z"),
		"electionTerm" : NumberLong(7),
		"lastCommittedOpTimeAtElection" : {
			"ts" : Timestamp(1605169711, 1),
			"t" : NumberLong(5)
		},
		"lastSeenOpTimeAtElection" : {
			"ts" : Timestamp(1605169711, 1),
			"t" : NumberLong(5)
		},
		"numVotesNeeded" : 2,
		"priorityAtElection" : 1,
		"electionTimeoutMillis" : NumberLong(10000),
		"numCatchUpOps" : NumberLong(0),
		"newTermStartDate" : ISODate("2020-11-12T08:28:42.125Z")
	},
	"members" : [
		{
			"_id" : 0,
			"name" : "10.10.10.11:27017",
			"health" : 0,
			"state" : 8,
			"stateStr" : "(not reachable/healthy)",
			"uptime" : 0,
			"optime" : {
				"ts" : Timestamp(0, 0),
				"t" : NumberLong(-1)
			},
			"optimeDurable" : {
				"ts" : Timestamp(0, 0),
				"t" : NumberLong(-1)
			},
			"optimeDate" : ISODate("1970-01-01T00:00:00Z"),
			"optimeDurableDate" : ISODate("1970-01-01T00:00:00Z"),
			"lastHeartbeat" : ISODate("2020-11-12T08:30:10.207Z"),
			"lastHeartbeatRecv" : ISODate("2020-11-12T08:28:31.380Z"),
			"pingMs" : NumberLong(0),
			"lastHeartbeatMessage" : "Error connecting to 10.10.10.11:27017 :: caused by :: Connection refused",
			"syncSourceHost" : "",
			"syncSourceId" : -1,
			"infoMessage" : "",
			"configVersion" : 3,
			"configTerm" : 5
		},
		{
			"_id" : 1,
			"name" : "10.10.10.11:27018",
			"health" : 1,
			"state" : 1,
			"stateStr" : "PRIMARY",
			"uptime" : 1537,
			"optime" : {
				"ts" : Timestamp(1605169802, 1),
				"t" : NumberLong(7)
			},
			"optimeDate" : ISODate("2020-11-12T08:30:02Z"),
			"syncSourceHost" : "",
			"syncSourceId" : -1,
			"infoMessage" : "",
			"electionTime" : Timestamp(1605169722, 1),
			"electionDate" : ISODate("2020-11-12T08:28:42Z"),
			"configVersion" : 3,
			"configTerm" : 7,
			"self" : true,
			"lastHeartbeatMessage" : ""
		},
		{
			"_id" : 2,
			"name" : "10.10.10.11:27019",
			"health" : 1,
			"state" : 7,
			"stateStr" : "ARBITER",
			"uptime" : 1534,
			"lastHeartbeat" : ISODate("2020-11-12T08:30:10.162Z"),
			"lastHeartbeatRecv" : ISODate("2020-11-12T08:30:10.165Z"),
			"pingMs" : NumberLong(0),
			"lastHeartbeatMessage" : "",
			"syncSourceHost" : "",
			"syncSourceId" : -1,
			"infoMessage" : "",
			"configVersion" : 3,
			"configTerm" : 7
		}
	],
	"ok" : 1,
	"$clusterTime" : {
		"clusterTime" : Timestamp(1605169802, 1),
		"signature" : {
			"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
			"keyId" : NumberLong(0)
		}
	},
	"operationTime" : Timestamp(1605169802, 1)
}

经过上面查看以前的27018副本节点已经变为了主节点，接下来在副本节点中插入数据

myrs:PRIMARY> use collectest
switched to db collectest
myrs:PRIMARY> db.collectest.insert({"name":"小嘿", "sex":"女", "age":21, "userid":1002, "createdatetime":new Date()})
WriteResult({ "nInserted" : 1 })

此时，从新启动27017节点，并查看状态

# mongod -f /data/replica_sets/myrs_27017/mongod.conf
# mongo --host=10.10.10.11 --port=27017
myrs:SECONDARY> 
myrs:SECONDARY> rs.secondaryOk()
myrs:SECONDARY> use collectest
switched to db collectest
myrs:SECONDARY> db.collectest.find()
{ "_id" : ObjectId("5faa3432f6e79c62c00e4d72"), "name" : "张三", "sex" : "男", "age" : 22, "userid" : 1001, "createdatetime" : ISODate("2020-11-10T06:33:22.459Z") }
{ "_id" : ObjectId("5facec10cca53c48154d261c"), "name" : "小白", "sex" : "女", "age" : 20, "userid" : 1002, "createdatetime" : ISODate("2020-11-12T08:02:24.915Z") }
{ "_id" : ObjectId("5facf32dfb5fe16aaf699d7d"), "name" : "小嘿", "sex" : "女", "age" : 21, "userid" : 1002, "createdatetime" : ISODate("2020-11-12T08:32:45.919Z") }

经过上面测试发现，此时27017节点已经变成了副本节点，而且配置查看权限后，能够对数据进行查看操做。

经过上面的测试，主从自动切换，故而试下了高可用。

仲裁节点和主节点故障

先关掉仲裁节点27019

关掉如今的主节点27018

登录27017后，发现，27017仍然是从节点，副本集中没有主节点了，致使此时，副本集只是读状态，没法写入。

为啥不选举了？由于27017的票数，没有得到大多数，即没有大于等于2，它只有默认的一票（优先级是1）

若是要触发选举，随便加入一个成员便可。

若是只加入27019仲裁节点成员，则主节点必定是27017，由于没得选了，仲裁节点不参与选举，但参与投票
若是只加入27018节点，会发起选举。由于27017和27018都是两票，则按照谁数据新，谁当主节点。