Install MongoDB replica set under Centos

Simulate the installation of a replica set of MongoDB under a Centos

Prepare three profiles:

mongod.conf

bind_ip=0.0.0.0
port = 27017
dbpath = /usr/local/mongo/data/
logpath = /usr/local/mongo/log/mongod.log
fork=true
logappend=true
replSet=myMongoSet

mongod2.conf

bind_ip=0.0.0.0
port = 27018
dbpath = /usr/local/mongo/data2/
logpath = /usr/local/mongo/log2/mongod.log
fork=true
logappend=true
replSet=myMongoSet

mongod3.conf

bind_ip=0.0.0.0
port = 27019
dbpath = /usr/local/mongo/data3/
logpath = /usr/local/mongo/log3/mongod.log
fork=true
logappend=true
replSet=myMongoSet

Start three mongo instances in the bin directory

./mongod -f ../conf/mongod.conf 
./mongod -f ../conf/mongod2.conf 
./mongod -f ../conf/mongod3.conf

View the process to verify that three MongoDB instances started successfully

[root@192 conf]# ps -ef | grep mongod
root        559 130632  0 14:53 pts/1    00:00:00 grep --color=auto mongod
root     130957      1  0 14:37 ?        00:00:04 ./mongod -f ../conf/mongod.conf
root     130986      1  0 14:37 ?        00:00:04 ./mongod -f ../conf/mongod2.conf
root     131014      1  0 14:37 ?        00:00:04 ./mongod -f ../conf/mongod3.conf

Indicates that three MongoDB instances have been started successfully

Connect the first mongo

./mongo 192.168.15.31:27017/admin

Preparing to initialize the instance

> config={_id:"myMongoSet",members:[{_id:0,host:"192.168.15.31:27017"},{_id:1,host:"192.168.15.31:27018"},{_id:2,host:"192.168.15.31:27019"}]}
{
	"_id" : "myMongoSet",
	"members" : [
		{
			"_id" : 0,
			"host" : "192.168.15.31:27017"
		},
		{
			"_id" : 1,
			"host" : "192.168.15.31:27018"
		},
		{
			"_id" : 2,
			"host" : "192.168.15.31:27019"
		}
	]
}

Define config content as instance information for the cluster

> rs.initiate(config)

Initialize replica set

The output after execution is as follows:

{
	"ok" : 1,
	"operationTime" : Timestamp(1517640358, 1),
	"$clusterTime" : {
		"clusterTime" : Timestamp(1517640358, 1),
		"signature" : {
			"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
			"keyId" : NumberLong(0)
		}
	}
}

Describes MongoDB’s replica set creation success

View replica set status

myMongoSet:SECONDARY> rs.status()
{
	"set" : "myMongoSet",
	"date" : ISODate("2018-02-03T06:46:09.449Z"),
	"myState" : 1,
	"term" : NumberLong(1),
	"heartbeatIntervalMillis" : NumberLong(2000),
	"optimes" : {
		"lastCommittedOpTime" : {
			"ts" : Timestamp(0, 0),
			"t" : NumberLong(-1)
		},
		"appliedOpTime" : {
			"ts" : Timestamp(1517640358, 1),
			"t" : NumberLong(-1)
		},
		"durableOpTime" : {
			"ts" : Timestamp(1517640358, 1),
			"t" : NumberLong(-1)
		}
	},
	"members" : [
		{
			"_id" : 0,
			"name" : "192.168.15.31:27017",
			"health" : 1,
			"state" : 1,
			"stateStr" : "PRIMARY",
			"uptime" : 546,
			"optime" : {
				"ts" : Timestamp(1517640358, 1),
				"t" : NumberLong(-1)
			},
			"optimeDate" : ISODate("2018-02-03T06:45:58Z"),
			"infoMessage" : "could not find member to sync from",
			"electionTime" : Timestamp(1517640368, 1),
			"electionDate" : ISODate("2018-02-03T06:46:08Z"),
			"configVersion" : 1,
			"self" : true
		},
		{
			"_id" : 1,
			"name" : "192.168.15.31:27018",
			"health" : 1,
			"state" : 2,
			"stateStr" : "SECONDARY",
			"uptime" : 10,
			"optime" : {
				"ts" : Timestamp(1517640358, 1),
				"t" : NumberLong(-1)
			},
			"optimeDurable" : {
				"ts" : Timestamp(1517640358, 1),
				"t" : NumberLong(-1)
			},
			"optimeDate" : ISODate("2018-02-03T06:45:58Z"),
			"optimeDurableDate" : ISODate("2018-02-03T06:45:58Z"),
			"lastHeartbeat" : ISODate("2018-02-03T06:46:08.931Z"),
			"lastHeartbeatRecv" : ISODate("2018-02-03T06:46:05.733Z"),
			"pingMs" : NumberLong(0),
			"configVersion" : 1
		},
		{
			"_id" : 2,
			"name" : "192.168.15.31:27019",
			"health" : 1,
			"state" : 2,
			"stateStr" : "SECONDARY",
			"uptime" : 10,
			"optime" : {
				"ts" : Timestamp(1517640358, 1),
				"t" : NumberLong(-1)
			},
			"optimeDurable" : {
				"ts" : Timestamp(1517640358, 1),
				"t" : NumberLong(-1)
			},
			"optimeDate" : ISODate("2018-02-03T06:45:58Z"),
			"optimeDurableDate" : ISODate("2018-02-03T06:45:58Z"),
			"lastHeartbeat" : ISODate("2018-02-03T06:46:08.932Z"),
			"lastHeartbeatRecv" : ISODate("2018-02-03T06:46:05.734Z"),
			"pingMs" : NumberLong(0),
			"configVersion" : 1
		}
	],
	"ok" : 1,
	"operationTime" : Timestamp(1517640358, 1),
	"$clusterTime" : {
		"clusterTime" : Timestamp(1517640368, 1),
		"signature" : {
			"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
			"keyId" : NumberLong(0)
		}
	}
}

Verify data synchronization:

Connect 27017 instances:

myMongoSet:PRIMARY>use stu
myMongoSet:PRIMARY> db.stuinfo.insert({"name":"Zhang San","age":12,"address":"Shandong"})

Query adds:

myMongoSet:PRIMARY> db.stuinfo.find()
{ "_id" : ObjectId("5a755b6a4dfb8ddaa17bad20"), "name" : "Zhang San", "age" : 12, "address" : "Shandong" }

Enter 27018 instances:

myMongoSet:SECONDARY> db.stuinfo.find()
Error: error: {
	"operationTime" : Timestamp(1517641210, 1),
	"ok" : 0,
	"errmsg" : "not master and slaveOk=false",
	"code" : 13435,
	"codeName" : "NotMasterNoSlaveOk",
	"$clusterTime" : {
		"clusterTime" : Timestamp(1517641210, 1),
		"signature" : {
			"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
			"keyId" : NumberLong(0)
		}
	}
}

Viewing the information may cause the above problem because MongoDB’s salve defaults to not allow reading and writing. Solution:

myMongoSet:SECONDARY> rs.slaveOk()

See if the information is synchronized:

myMongoSet:SECONDARY> use stu
switched to db stu
myMongoSet:SECONDARY> db.stuinfo.find()
{ "_id" : ObjectId("5a755b6a4dfb8ddaa17bad20"), "name" : "Zhang San", "age" : 12, "address" : "Shandong" }

Connect instance 27019 and do the same. Thus, the data information can be synchronized correctly. So far, MongoDB’s replica set has been successfully set up

Verify master-slave switching:

Now the primary node is 27017, we kill the process

[root@192 bin]# ps -ef | grep mongod
root        659 130632  0 15:05 pts/1    00:00:00 grep --color=auto mongod
root     130957      1  0 14:37 ?        00:00:08 ./mongod -f ../conf/mongod.conf
root     130986      1  0 14:37 ?        00:00:08 ./mongod -f ../conf/mongod2.conf
root     131014      1  0 14:37 ?        00:00:08 ./mongod -f ../conf/mongod3.conf
[root@192 bin]# kill 130957
[root@192 bin]# ps -ef | grep mongod
root        674 130632  0 15:05 pts/1    00:00:00 grep --color=auto mongod
root     130986      1  0 14:37 ?        00:00:08 ./mongod -f ../conf/mongod2.conf
root     131014      1  0 14:37 ?        00:00:08 ./mongod -f ../conf/mongod3.conf

The process has been killed

Then connect 27018 nodes

[root@192 bin]# ./mongo 192.168.15.31:27018
MongoDB shell version v3.6.2
connecting to: mongodb://192.168.15.31:27018/test
MongoDB server version: 3.6.2
Server has startup warnings: 
2018-02-03T14:37:09.007+0800 I CONTROL  [initandlisten] 
2018-02-03T14:37:09.007+0800 I CONTROL  [initandlisten] ** WARNING: Access control is not enabled for the database.
2018-02-03T14:37:09.007+0800 I CONTROL  [initandlisten] **          Read and write access to data and configuration is unrestricted.
2018-02-03T14:37:09.007+0800 I CONTROL  [initandlisten] ** WARNING: You are running this process as the root user, which is not recommended.
2018-02-03T14:37:09.007+0800 I CONTROL  [initandlisten] 
2018-02-03T14:37:09.007+0800 I CONTROL  [initandlisten] 
2018-02-03T14:37:09.007+0800 I CONTROL  [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'.
2018-02-03T14:37:09.007+0800 I CONTROL  [initandlisten] **        We suggest setting it to 'never'
2018-02-03T14:37:09.007+0800 I CONTROL  [initandlisten] 
2018-02-03T14:37:09.007+0800 I CONTROL  [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is 'always'.
2018-02-03T14:37:09.007+0800 I CONTROL  [initandlisten] **        We suggest setting it to 'never'
2018-02-03T14:37:09.007+0800 I CONTROL  [initandlisten] 
myMongoSet:PRIMARY>

As you can see, 27018 node has become the primary node

Then reopen 27017 nodes

[root@192 bin]# ./mongod -f ../conf/mongod.conf 
about to fork child process, waiting until server is ready for connections.
forked process: 703
child process started successfully, parent exiting

Connect 27017 Nodes

[root@192 bin]# ./mongo 192.168.15.31:27017
MongoDB shell version v3.6.2
connecting to: mongodb://192.168.15.31:27017/test
MongoDB server version: 3.6.2
Server has startup warnings: 
2018-02-03T15:07:54.488+0800 I CONTROL  [initandlisten] 
2018-02-03T15:07:54.488+0800 I CONTROL  [initandlisten] ** WARNING: Access control is not enabled for the database.
2018-02-03T15:07:54.488+0800 I CONTROL  [initandlisten] **          Read and write access to data and configuration is unrestricted.
2018-02-03T15:07:54.488+0800 I CONTROL  [initandlisten] ** WARNING: You are running this process as the root user, which is not recommended.
2018-02-03T15:07:54.488+0800 I CONTROL  [initandlisten] 
2018-02-03T15:07:54.488+0800 I CONTROL  [initandlisten] 
2018-02-03T15:07:54.488+0800 I CONTROL  [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'.
2018-02-03T15:07:54.488+0800 I CONTROL  [initandlisten] **        We suggest setting it to 'never'
2018-02-03T15:07:54.488+0800 I CONTROL  [initandlisten] 
2018-02-03T15:07:54.488+0800 I CONTROL  [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is 'always'.
2018-02-03T15:07:54.488+0800 I CONTROL  [initandlisten] **        We suggest setting it to 'never'
2018-02-03T15:07:54.488+0800 I CONTROL  [initandlisten] 
myMongoSet:SECONDARY>