解決思路
- 爲了保證數據的一致性，需要先停止應用對數據庫的讀寫
- 修改要切換爲主節點Primary的Secondary節點的優先級
- 重新配置config
解決方式
數據庫通過shell登錄Primary節點，這是因爲修改必須要Primary節點纔可以。通過rs.status()查看當前副本集狀態，找到members需要切換爲Primary節點的數組下標，將其優先級priority設置成members中最大的值，rs.conf()獲取到當前配置，重新配置rs.reconfig(config)就修改成功了。
執行命令：
mongos:PRIMARY> config = rs.conf()
mongos:PRIMARY> config.members[1].priority=2
mongos:PRIMARY> rs.reconfig(config)
以下是詳細的過程輸出：
mongos:PRIMARY> config = rs.conf()
{
"_id" : "mongos",
"version" : 1,
"protocolVersion" : NumberLong(1),
"writeConcernMajorityJournalDefault" : true,
"members" : [
{
"_id" : 0,
"host" : "172.21.0.1:27017",
"arbiterOnly" : false,
"buildIndexes" : true,
"hidden" : false,
"priority" : 1,
"tags" : {
},
"slaveDelay" : NumberLong(0),
"votes" : 1
},
{
"_id" : 1,
"host" : "172.21.0.1:27018",
"arbiterOnly" : false,
"buildIndexes" : true,
"hidden" : false,
"priority" : 1,
"tags" : {
},
"slaveDelay" : NumberLong(0),
"votes" : 1
},
{
"_id" : 2,
"host" : "172.21.0.1:27019",
"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("5cf69637809c46464bcd13cc")
}
}
mongos:PRIMARY> config.members[0].priority=2
2
mongos:PRIMARY> rs.reconfig(config)
{
"ok" : 1,
"operationTime" : Timestamp(1562597866, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1562597866, 1),
"signature" : {
"hash" : BinData(0,"pS59GbmLjln3v8nK+1Gc4ToQDSE="),
"keyId" : NumberLong("6698706710267166722")
}
}
}
mongos:PRIMARY>
mongos:PRIMARY> rs.status()
2019-07-08T14:58:17.111+0000 E QUERY [js] Error: error doing query: failed: network error while attempting to run command 'replSetGetStatus' on host '172.21.0.1:27018' :
DB.prototype.runCommand@src/mongo/shell/db.js:168:1
DB.prototype.adminCommand@src/mongo/shell/db.js:186:16
rs.status@src/mongo/shell/utils.js:1360:12
@(shell):1:1
2019-07-08T14:58:17.113+0000 I NETWORK [js] trying reconnect to 172.21.0.1:27018 failed
2019-07-08T14:58:17.116+0000 I NETWORK [js] reconnect 172.21.0.1:27018 ok
mongos:SECONDARY>
mongos:SECONDARY> rs.status()
{
"set" : "mongos",
"date" : ISODate("2019-07-08T14:58:20.646Z"),
"myState" : 2,
"term" : NumberLong(6),
"syncingTo" : "172.21.0.1:27017",
"syncSourceHost" : "172.21.0.1:27017",
"syncSourceId" : 0,
"heartbeatIntervalMillis" : NumberLong(2000),
"optimes" : {
"lastCommittedOpTime" : {
"ts" : Timestamp(1562597898, 1),
"t" : NumberLong(6)
},
"readConcernMajorityOpTime" : {
"ts" : Timestamp(1562597898, 1),
"t" : NumberLong(6)
},
"appliedOpTime" : {
"ts" : Timestamp(1562597898, 1),
"t" : NumberLong(6)
},
"durableOpTime" : {
"ts" : Timestamp(1562597898, 1),
"t" : NumberLong(6)
}
},
"lastStableCheckpointTimestamp" : Timestamp(1562597878, 1),
"members" : [
{
"_id" : 0,
"name" : "172.21.0.1:27017",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 9562,
"optime" : {
"ts" : Timestamp(1562597898, 1),
"t" : NumberLong(6)
},
"optimeDurable" : {
"ts" : Timestamp(1562597898, 1),
"t" : NumberLong(6)
},
"optimeDate" : ISODate("2019-07-08T14:58:18Z"),
"optimeDurableDate" : ISODate("2019-07-08T14:58:18Z"),
"lastHeartbeat" : ISODate("2019-07-08T14:58:19.244Z"),
"lastHeartbeatRecv" : ISODate("2019-07-08T14:58:18.820Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "",
"syncingTo" : "",
"syncSourceHost" : "",
"syncSourceId" : -1,
"infoMessage" : "",
"electionTime" : Timestamp(1562597876, 1),
"electionDate" : ISODate("2019-07-08T14:57:56Z"),
"configVersion" : 2
},
{
"_id" : 1,
"name" : "172.21.0.1:27018",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 9567,
"optime" : {
"ts" : Timestamp(1562597898, 1),
"t" : NumberLong(6)
},
"optimeDate" : ISODate("2019-07-08T14:58:18Z"),
"syncingTo" : "172.21.0.1:27017",
"syncSourceHost" : "172.21.0.1:27017",
"syncSourceId" : 0,
"infoMessage" : "",
"configVersion" : 2,
"self" : true,
"lastHeartbeatMessage" : ""
},
{
"_id" : 2,
"name" : "172.21.0.1:27019",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 9562,
"optime" : {
"ts" : Timestamp(1562597898, 1),
"t" : NumberLong(6)
},
"optimeDurable" : {
"ts" : Timestamp(1562597898, 1),
"t" : NumberLong(6)
},
"optimeDate" : ISODate("2019-07-08T14:58:18Z"),
"optimeDurableDate" : ISODate("2019-07-08T14:58:18Z"),
"lastHeartbeat" : ISODate("2019-07-08T14:58:19.244Z"),
"lastHeartbeatRecv" : ISODate("2019-07-08T14:58:19.289Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "",
"syncingTo" : "172.21.0.1:27017",
"syncSourceHost" : "172.21.0.1:27017",
"syncSourceId" : 0,
"infoMessage" : "",
"configVersion" : 2
}
],
"ok" : 1,
"operationTime" : Timestamp(1562597898, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1562597898, 1),
"signature" : {
"hash" : BinData(0,"g+x+Tlz22VNUuyNvHQztuxkE6J0="),
"keyId" : NumberLong("6698706710267166722")
}
}
}
mongos:SECONDARY>
執行查看rs.status()過程中出現這個報錯，是因爲修改配置後正在重啓，稍等一會就切換成功，再次回車會發現當前節點已經變成了Secondary節點
mongos:PRIMARY> rs.status()
2019-07-08T14:58:17.111+0000 E QUERY [js] Error: error doing query: failed: network error while attempting to run command 'replSetGetStatus' on host '172.21.0.1:27018' :
DB.prototype.runCommand@src/mongo/shell/db.js:168:1
DB.prototype.adminCommand@src/mongo/shell/db.js:186:16
rs.status@src/mongo/shell/utils.js:1360:12
@(shell):1:1
2019-07-08T14:58:17.113+0000 I NETWORK [js] trying reconnect to 172.21.0.1:27018 failed
2019-07-08T14:58:17.116+0000 I NETWORK [js] reconnect 172.21.0.1:27018 ok
mongos:SECONDARY>
至此，手動切換Primary節點就完成了。