项目环境：

CentOS 7.5

MongoDB 4.2.12

一、配置参数文件

172.16.254.131

dbpath=/mongodb/data
logpath=/mongodb/logs/mongodb.log
port=27017
fork=true
#auth=true
noauth=true
#verbose=true
#vvvv=true
journal = true
maxConns=500
logappend=true
directoryperdb=true
#pidfilepath=/var/run/mongo.pid
#cpu=true
#nohttpinterface=false
#notablescan=false
#profile=0
#slowms=200
#quiet=true
#syncdelay=60
bind_ip=0.0.0.0
replSet=handong1

172.16.254.132

dbpath=/mongodb/data
logpath=/mongodb/logs/mongodb.log
port=27017
fork=true
#auth=true
noauth=true
#verbose=true
#vvvv=true
journal = true
maxConns=500
logappend=true
directoryperdb=true
#pidfilepath=/var/run/mongo.pid
#cpu=true
#nohttpinterface=false
#notablescan=false
#profile=0
#slowms=200
#quiet=true
#syncdelay=60
bind_ip=0.0.0.0
replSet=handong1

172.16.254.133

dbpath=/mongodb/data
logpath=/mongodb/logs/mongodb.log
port=27017
fork=true
#auth=true
noauth=true
#verbose=true
#vvvv=true
journal = true
maxConns=500
logappend=true
directoryperdb=true
#pidfilepath=/var/run/mongo.pid
#cpu=true
#nohttpinterface=false
#notablescan=false
#profile=0
#slowms=200
#quiet=true
#syncdelay=60
bind_ip=0.0.0.0
replSet=handong1

二、启动mongodb服务

三个节点执行：

mongod -f /mongodb/conf/mongodb.conf 
about to fork child process, waiting until server is ready for connections.
forked process: 23212
child process started successfully, parent exiting

三、配置副本集
在计划的主节点执行：

rs.initiate({_id:"handong1",members:[{_id:0,host:"mongo1:27017"},{_id:1,host:"mongo2:27017"},{_id:2,host:"mongo3:27017",arbiterOnly:true}]}

查看副本集状态：

handong1:PRIMARY> rs.status()
{
	"set" : "handong1",
	"date" : ISODate("2021-03-18T09:28:47.224Z"),
	"myState" : 1,
	"term" : NumberLong(3),
	"syncingTo" : "",
	"syncSourceHost" : "",
	"syncSourceId" : -1,
	"heartbeatIntervalMillis" : NumberLong(2000),
	"majorityVoteCount" : 2,
	"writeMajorityCount" : 2,
	"optimes" : {
		"lastCommittedOpTime" : {
			"ts" : Timestamp(1616059724, 1),
			"t" : NumberLong(3)
		},
		"lastCommittedWallTime" : ISODate("2021-03-18T09:28:44.052Z"),
		"readConcernMajorityOpTime" : {
			"ts" : Timestamp(1616059724, 1),
			"t" : NumberLong(3)
		},
		"readConcernMajorityWallTime" : ISODate("2021-03-18T09:28:44.052Z"),
		"appliedOpTime" : {
			"ts" : Timestamp(1616059724, 1),
			"t" : NumberLong(3)
		},
		"durableOpTime" : {
			"ts" : Timestamp(1616059724, 1),
			"t" : NumberLong(3)
		},
		"lastAppliedWallTime" : ISODate("2021-03-18T09:28:44.052Z"),
		"lastDurableWallTime" : ISODate("2021-03-18T09:28:44.052Z")
	},
	"lastStableRecoveryTimestamp" : Timestamp(1616059657, 1),
	"lastStableCheckpointTimestamp" : Timestamp(1616059657, 1),
	"electionCandidateMetrics" : {
		"lastElectionReason" : "electionTimeout",
		"lastElectionDate" : ISODate("2021-03-18T09:05:47.089Z"),
		"electionTerm" : NumberLong(3),
		"lastCommittedOpTimeAtElection" : {
			"ts" : Timestamp(0, 0),
			"t" : NumberLong(-1)
		},
		"lastSeenOpTimeAtElection" : {
			"ts" : Timestamp(1616055916, 1),
			"t" : NumberLong(2)
		},
		"numVotesNeeded" : 1,
		"priorityAtElection" : 1,
		"electionTimeoutMillis" : NumberLong(10000),
		"newTermStartDate" : ISODate("2021-03-18T09:05:47.098Z"),
		"wMajorityWriteAvailabilityDate" : ISODate("2021-03-18T09:05:47.129Z")
	},
	"members" : [
		{
			"_id" : 0,
			"name" : "172.16.254.131:27017",
			"health" : 1,
			"state" : 1,
			"stateStr" : "PRIMARY",
			"uptime" : 1383,
			"optime" : {
				"ts" : Timestamp(1616059724, 1),
				"t" : NumberLong(3)
			},
			"optimeDate" : ISODate("2021-03-18T09:28:44Z"),
			"syncingTo" : "",
			"syncSourceHost" : "",
			"syncSourceId" : -1,
			"infoMessage" : "",
			"electionTime" : Timestamp(1616058347, 1),
			"electionDate" : ISODate("2021-03-18T09:05:47Z"),
			"configVersion" : 6,
			"self" : true,
			"lastHeartbeatMessage" : ""
		},
		{
			"_id" : 1,
			"name" : "mongo2:27017",
			"health" : 1,
			"state" : 2,
			"stateStr" : "SECONDARY",
			"uptime" : 28,
			"optime" : {
				"ts" : Timestamp(1616059724, 1),
				"t" : NumberLong(3)
			},
			"optimeDurable" : {
				"ts" : Timestamp(1616059724, 1),
				"t" : NumberLong(3)
			},
			"optimeDate" : ISODate("2021-03-18T09:28:44Z"),
			"optimeDurableDate" : ISODate("2021-03-18T09:28:44Z"),
			"lastHeartbeat" : ISODate("2021-03-18T09:28:46.063Z"),
			"lastHeartbeatRecv" : ISODate("2021-03-18T09:28:46.065Z"),
			"pingMs" : NumberLong(1),
			"lastHeartbeatMessage" : "",
			"syncingTo" : "172.16.254.131:27017",
			"syncSourceHost" : "172.16.254.131:27017",
			"syncSourceId" : 0,
			"infoMessage" : "",
			"configVersion" : 6
		},
		{
			"_id" : 2,
			"name" : "mongo3:27017",
			"health" : 1,
			"state" : 7,
			"stateStr" : "ARBITER",
			"uptime" : 1,
			"lastHeartbeat" : ISODate("2021-03-18T09:28:46.063Z"),
			"lastHeartbeatRecv" : ISODate("2021-03-18T09:28:46.072Z"),
			"pingMs" : NumberLong(0),
			"lastHeartbeatMessage" : "",
			"syncingTo" : "",
			"syncSourceHost" : "",
			"syncSourceId" : -1,
			"infoMessage" : "",
			"configVersion" : 6
		}
	],
	"ok" : 1,
	"$clusterTime" : {
		"clusterTime" : Timestamp(1616059724, 1),
		"signature" : {
			"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
			"keyId" : NumberLong(0)
		}
	},
	"operationTime" : Timestamp(1616059724, 1)
}

四、验证副本集

172.16.254.131

handong1:PRIMARY> use db3
switched to db db3
handong1:PRIMARY> db.db3.insert({"name":"mongodb4.2"})
WriteResult({ "nInserted" : 1 })

172.16.254.132

handong1:SECONDARY> rs.secondaryOk();
handong1:SECONDARY> db.db3.find()
{ "_id" : ObjectId("6051d08ac74d627f4b561349"), "name" : "mongodb" }
{ "_id" : ObjectId("6053225bdebdeda2639f026e"), "name" : "mongodb4.2" }

数据已经同步过来