MongoDB 副本集切換方法
阿新 • • 發佈:2020-08-05
1、rs.stepDown([stepdownSecs, catchUpSecs]) step down as primary (disconnects)
這個命令會將primary降級為Secondary節點
登陸primary節點
[root@127-0-0-1 conf]# mongo --port 2777 shard1:PRIMARY> show dbs admin 0.000GB config 0.000GB local 0.001GB yoon 0.000GB
通過 help 幫助檢視各種命令
shard1:PRIMARY> rs.help() rs.status() { replSetGetStatus :1 } checks repl set status rs.initiate() { replSetInitiate : null } initiates set with default settings rs.initiate(cfg) { replSetInitiate : cfg } initiates set with configuration cfg rs.conf() get the current configuration objectfrom local.system.replset rs.reconfig(cfg) updates the configuration of a running replica set with cfg (disconnects) rs.add(hostportstr) add a new member to the set with default attributes (disconnects) rs.add(membercfgobj) add anew member to the set with extra attributes (disconnects) rs.addArb(hostportstr) add a new member which is arbiterOnly:true (disconnects) rs.stepDown([stepdownSecs, catchUpSecs]) step down as primary (disconnects) rs.syncFrom(hostportstr) make a secondary sync from the given member rs.freeze(secs) make a node ineligible to become primary for the time specified rs.remove(hostportstr) remove a host from the replica set (disconnects) rs.slaveOk() allow queries on secondary nodes rs.printReplicationInfo() check oplog size and time range rs.printSlaveReplicationInfo() check replica set members and replication lag db.isMaster() check who is primary reconfiguration helpers disconnect from the database so the shell will display an error, even if the command succeeds.
將primary降級為Secondary節點
shard1:PRIMARY> rs.stepDown()
這個命令會讓primary降級為Secondary節點並維持30S,如果這段時間沒有新的primary選舉出來,這個節點重新加入進行選舉
shard1:PRIMARY> rs.stepDown(30)
2、通過設定優先順序
A.為了保證資料的一致性,必須先關閉應用的寫服務
B.提升要升級為primary節點的Secondary節點的優先順序
檢視當前配置資訊:
shard1:PRIMARY> rs.conf() { "_id" : "shard1", "version" : 4, "protocolVersion" : NumberLong(1), "writeConcernMajorityJournalDefault" : true, "members" : [ { "_id" : 0, "host" : "127.0.0.1:2777", "arbiterOnly" : false, "buildIndexes" : true, "hidden" : false, "priority" : 3, "tags" : { }, "slaveDelay" : NumberLong(0), "votes" : 1 }, { "_id" : 1, "host" : "127.0.0.1:3777", "arbiterOnly" : false, "buildIndexes" : true, "hidden" : false, "priority" : 1, "tags" : { }, "slaveDelay" : NumberLong(0), "votes" : 1 }, { "_id" : 2, "host" : "127.0.0.1:4777", "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("5f27de76c8d22581cdeb2f2e") } }
檢視當前配置,存入config變數中
shard1:PRIMARY> config=rs.conf()
修改config變數,將第三組埠為4777的成員優先順序設定為3
hard1:PRIMARY> config.members[2].priority = 3
配置生效
shard1:PRIMARY> rs.reconfig(config)
檢視切換後的節點資訊
shard1:PRIMARY> db.isMaster() { "hosts" : [ "127.0.0.1:2777", "127.0.0.1:3777", "127.0.0.1:4777" ], "setName" : "shard1", "setVersion" : 7, "ismaster" : true, "secondary" : false, "primary" : "127.0.0.1:4777", "me" : "127.0.0.1:4777", "electionId" : ObjectId("7fffffff0000000000000004"), "lastWrite" : { "opTime" : { "ts" : Timestamp(1596599298, 1), "t" : NumberLong(4) }, "lastWriteDate" : ISODate("2020-08-05T03:48:18Z"), "majorityOpTime" : { "ts" : Timestamp(1596599298, 1), "t" : NumberLong(4) }, "majorityWriteDate" : ISODate("2020-08-05T03:48:18Z") }.. ...