mongodb副本集主从切换
前文已有mongodb副本集搭建及添加节点的记录
本次进行主从切换及删除节点的操作。
1. 主从切换
1.1 查询当前节点信息及状态
使用rs.status()命令可以查看到当前副本集各节点信息及角色
| 节点id | 节点 | 角色 |
| node0 | 192.168.56.198:27017 | PRIMARY |
| node1 | 192.168.56.199:27018 | ARBITER |
| node2 | 192.168.56.197:27017 | SECONDARY |
| node3 | 192.168.56.199:27017 | SECONDARY |
test12:PRIMARY> rs.status(){"set" : "test12","date" : ISODate("2021-12-16T13:45:28.261Z"),"myState" : 1,"term" : NumberLong(3),"syncingTo" : "","syncSourceHost" : "","syncSourceId" : -1,"heartbeatIntervalMillis" : NumberLong(2000),"majorityVoteCount" : 3,"writeMajorityCount" : 3,"optimes" : {"lastCommittedOpTime" : {"ts" : Timestamp(1639662318, 1),"t" : NumberLong(3)},"lastCommittedWallTime" : ISODate("2021-12-16T13:45:18.626Z"),"readConcernMajorityOpTime" : {"ts" : Timestamp(1639662318, 1),"t" : NumberLong(3)},"readConcernMajorityWallTime" : ISODate("2021-12-16T13:45:18.626Z"),"appliedOpTime" : {"ts" : Timestamp(1639662318, 1),"t" : NumberLong(3)},"durableOpTime" : {"ts" : Timestamp(1639662318, 1),"t" : NumberLong(3)},"lastAppliedWallTime" : ISODate("2021-12-16T13:45:18.626Z"),"lastDurableWallTime" : ISODate("2021-12-16T13:45:18.626Z")},"lastStableRecoveryTimestamp" : Timestamp(1639662308, 1),"lastStableCheckpointTimestamp" : Timestamp(1639662308, 1),"electionCandidateMetrics" : {"lastElectionReason" : "priorityTakeover","lastElectionDate" : ISODate("2021-12-14T15:24:57.309Z"),"electionTerm" : NumberLong(3),"lastCommittedOpTimeAtElection" : {"ts" : Timestamp(1639495485, 1),"t" : NumberLong(2)},"lastSeenOpTimeAtElection" : {"ts" : Timestamp(1639495485, 1),"t" : NumberLong(2)},"numVotesNeeded" : 3,"priorityAtElection" : 15,"electionTimeoutMillis" : NumberLong(10000),"priorPrimaryMemberId" : 3,"numCatchUpOps" : NumberLong(0),"newTermStartDate" : ISODate("2021-12-14T15:24:57.321Z"),"wMajorityWriteAvailabilityDate" : ISODate("2021-12-14T15:24:58.285Z")},"electionParticipantMetrics" : {"votedForCandidate" : true,"electionTerm" : NumberLong(2),"lastVoteDate" : ISODate("2021-12-14T10:36:13.063Z"),"electionCandidateMemberId" : 3,"voteReason" : "","lastAppliedOpTimeAtElection" : {"ts" : Timestamp(1639478166, 1),"t" : NumberLong(1)},"maxAppliedOpTimeInSet" : {"ts" : Timestamp(1639478166, 1),"t" : NumberLong(1)},"priorityAtElection" : 1},"members" : [{"_id" : 0,"name" : "192.168.56.198:27017","health" : 1,"state" : 1,"stateStr" : "PRIMARY","uptime" : 186852,"optime" : {"ts" : Timestamp(1639662318, 1),"t" : NumberLong(3)},"optimeDate" : ISODate("2021-12-16T13:45:18Z"),"syncingTo" : "","syncSourceHost" : "","syncSourceId" : -1,"infoMessage" : "","electionTime" : Timestamp(1639495497, 1),"electionDate" : ISODate("2021-12-14T15:24:57Z"),"configVersion" : 7,"self" : true,"lastHeartbeatMessage" : ""},{"_id" : 1,"name" : "192.168.56.199:27018","health" : 1,"state" : 7,"stateStr" : "ARBITER","uptime" : 186375,"lastHeartbeat" : ISODate("2021-12-16T13:45:27.183Z"),"lastHeartbeatRecv" : ISODate("2021-12-16T13:45:26.984Z"),"pingMs" : NumberLong(0),"lastHeartbeatMessage" : "","syncingTo" : "","syncSourceHost" : "","syncSourceId" : -1,"infoMessage" : "","configVersion" : 7},{"_id" : 2,"name" : "192.168.56.197:27017","health" : 1,"state" : 2,"stateStr" : "SECONDARY","uptime" : 185329,"optime" : {"ts" : Timestamp(1639662318, 1),"t" : NumberLong(3)},"optimeDurable" : {"ts" : Timestamp(1639662318, 1),"t" : NumberLong(3)},"optimeDate" : ISODate("2021-12-16T13:45:18Z"),"optimeDurableDate" : ISODate("2021-12-16T13:45:18Z"),"lastHeartbeat" : ISODate("2021-12-16T13:45:27.463Z"),"lastHeartbeatRecv" : ISODate("2021-12-16T13:45:26.387Z"),"pingMs" : NumberLong(1),"lastHeartbeatMessage" : "","syncingTo" : "192.168.56.198:27017","syncSourceHost" : "192.168.56.198:27017","syncSourceId" : 0,"infoMessage" : "","configVersion" : 7},{"_id" : 3,"name" : "192.168.56.199:27017","health" : 1,"state" : 2,"stateStr" : "SECONDARY","uptime" : 12079,"optime" : {"ts" : Timestamp(1639662318, 1),"t" : NumberLong(3)},"optimeDurable" : {"ts" : Timestamp(1639662318, 1),"t" : NumberLong(3)},"optimeDate" : ISODate("2021-12-16T13:45:18Z"),"optimeDurableDate" : ISODate("2021-12-16T13:45:18Z"),"lastHeartbeat" : ISODate("2021-12-16T13:45:28.253Z"),"lastHeartbeatRecv" : ISODate("2021-12-16T13:45:27.555Z"),"pingMs" : NumberLong(0),"lastHeartbeatMessage" : "","syncingTo" : "192.168.56.198:27017","syncSourceHost" : "192.168.56.198:27017","syncSourceId" : 0,"infoMessage" : "","configVersion" : 7}],"ok" : 1,"$clusterTime" : {"clusterTime" : Timestamp(1639662318, 1),"signature" : {"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),"keyId" : NumberLong(0)}},"operationTime" : Timestamp(1639662318, 1)}
1.2 切换主库
将主库切换至node3节点，具体步骤为：
查看当前配置
调整node3节点的权重
重新加载配置
因默认情况下，各节点的权重都为1，因此可以调整需要切换为主库的节点的权重为较大的值（建议超过节点数）
test12:PRIMARY> rs.config(){"_id" : "test12","version" : 9,"protocolVersion" : NumberLong(1),"writeConcernMajorityJournalDefault" : true,"members" : [{"_id" : 0,"host" : "192.168.56.198:27017","arbiterOnly" : false,"buildIndexes" : true,"hidden" : false,"priority" : 1,"tags" : {},"slaveDelay" : NumberLong(0),"votes" : 1},{"_id" : 1,"host" : "192.168.56.199:27018","arbiterOnly" : true,"buildIndexes" : true,"hidden" : false,"priority" : 0,"tags" : {},"slaveDelay" : NumberLong(0),"votes" : 1},{"_id" : 2,"host" : "192.168.56.197:27017","arbiterOnly" : false,"buildIndexes" : true,"hidden" : false,"priority" : 1,"tags" : {},"slaveDelay" : NumberLong(0),"votes" : 1},{"_id" : 3,"host" : "192.168.56.199:27017","arbiterOnly" : false,"buildIndexes" : true,"hidden" : false,"priority" : 1,"tags" : {},"slaveDelay" : NumberLong(0),"votes" : 1}],"settings" : {"chainingAllowed" : true,"heartbeatIntervalMillis" : 2000,"heartbeatTimeoutSecs" : 10,"electionTimeoutMillis" : 10000,"catchUpTimeoutMillis" : -1,"catchUpTakeoverDelayMillis" : 30000,"getLastErrorModes" : {},"getLastErrorDefaults" : {"w" : 1,"wtimeout" : 0},"replicaSetId" : ObjectId("61b86af0a21015e69623e18d")}}
将node3的节点的权重改为10
var cfg = rs.conf()cfg.members[3].priority = 10
重新加载配置，选主
rs.reconfig(cfg)通常1分钟内完成切换。
PS：也可以通过rs.stepDown()
PRIMARY> rs.stepDown() //rs.stepDown(30) 单位：S2. 剔除节点
剔除的节点为SECONDARY或ARBITER，可以执行通过rs.remove() 命令剔除对应节点，如为PRIMARY节点，则先进行主从切换，再剔除。test12:PRIMARY> rs.remove("192.168.56.199:27018"){"ok" : 1,"$clusterTime" : {"clusterTime" : Timestamp(1639683041, 1),"signature" : {"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),"keyId" : NumberLong(0)}},"operationTime" : Timestamp(1639683041, 1)}
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