mongodb副本集維護總結

參考：https://blog.51cto.com/caiyuanji
副本集維護：
副本集成員最多12個成員，其中只有7個成員擁有投票權。這是爲了減少 心跳請求的網絡流量和選舉話費的時間。心跳每2秒發送一次。
仲裁者唯一的作用就是參與選舉，仲裁者並不保存數據，也不會爲客戶端提供服務。成員一旦以仲裁者的身份加入副本集中，它就永遠只能是仲裁者，無法將仲裁者重新配置爲非仲裁者，反之亦然。最多只能有一個仲裁者每個副本集中。
修改副本集成員的優先級：
conf=rs.conf() #將rs.conf的值定義給conf
test:PRIMARY> conf.members[0].priority=3
3
test:PRIMARY> conf.members[1].priority=2
2
#這裏[0]並不是rs.status()裏的id號，而是誰在第一位誰就是0，從0開始。
test:PRIMARY> rs.reconfig(conf)
test:PRIMARY> rs.conf()
{
"_id" : "test",
"version" : 2,
"protocolVersion" : NumberLong(1),
"writeConcernMajorityJournalDefault" : true,
"members" : [
{
"_id" : 0,
"host" : "zhuzhu:27017",
"arbiterOnly" : false,
"buildIndexes" : true,
"hidden" : false,
"priority" : 100,
"tags" : {

        },
        "slaveDelay" : NumberLong(0),
        "votes" : 1
    },
    {
        "_id" : 1,
        "host" : "gougou:27017",
        "arbiterOnly" : false,
        "buildIndexes" : true,
        "hidden" : false,
        "priority" : 90,
        "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("5c2da4fc134c17137419c065")
}

}

主從切換成功
關於優先級範圍從0 至 1000 (3.2以上版本) ，優先級越大，越可能成爲primary；若優先級爲0，則該節點無資格參與primary的選舉。
如果希望某節點不參與primary的選舉有兩種方法： 1、將該節點優先級設置爲0；2、rs.freeze(30) 在cluster選舉primary時，將該節點暫時凍結30S。
如果希望將本primary節點降爲secondary狀態，可以執行 rs.stepDown() 。

在副本集中添加和刪除成員：
test:PRIMARY> rs.status() #查看副本集狀態
{
"set" : "test",
"date" : ISODate("2019-01-07T03:21:06.774Z"),
"myState" : 1,
"term" : NumberLong(13),
"syncingTo" : "",
"syncSourceHost" : "",
"syncSourceId" : -1,
"heartbeatIntervalMillis" : NumberLong(2000),
"optimes" : {
"lastCommittedOpTime" : {
"ts" : Timestamp(1546831263, 1),
"t" : NumberLong(13)
},
"readConcernMajorityOpTime" : {
"ts" : Timestamp(1546831263, 1),
"t" : NumberLong(13)
},
"appliedOpTime" : {
"ts" : Timestamp(1546831263, 1),
"t" : NumberLong(13)
},
"durableOpTime" : {
"ts" : Timestamp(1546831263, 1),
"t" : NumberLong(13)
}
},
"lastStableCheckpointTimestamp" : Timestamp(1546831238, 1),
"members" : [
{
"_id" : 0,
"name" : "zhuzhu:27017",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 1830,
"optime" : {
"ts" : Timestamp(1546831263, 1),
"t" : NumberLong(13)
},
"optimeDate" : ISODate("2019-01-07T03:21:03Z"),
"syncingTo" : "",
"syncSourceHost" : "",
"syncSourceId" : -1,
"infoMessage" : "",
"electionTime" : Timestamp(1546830032, 1),
"electionDate" : ISODate("2019-01-07T03:00:32Z"),
"configVersion" : 2,
"self" : true,
"lastHeartbeatMessage" : ""
},
{
"_id" : 1,
"name" : "gougou:27017",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 1251,
"optime" : {
"ts" : Timestamp(1546831263, 1),
"t" : NumberLong(13)
},
"optimeDurable" : {
"ts" : Timestamp(1546831263, 1),
"t" : NumberLong(13)
},
"optimeDate" : ISODate("2019-01-07T03:21:03Z"),
"optimeDurableDate" : ISODate("2019-01-07T03:21:03Z"),
"lastHeartbeat" : ISODate("2019-01-07T03:21:05.954Z"),
"lastHeartbeatRecv" : ISODate("2019-01-07T03:21:05.060Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "",
"syncingTo" : "zhuzhu:27017",
"syncSourceHost" : "zhuzhu:27017",
"syncSourceId" : 0,
"infoMessage" : "",
"configVersion" : 2
}
],
"ok" : 1,
"operationTime" : Timestamp(1546831263, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1546831263, 1),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
}
test:PRIMARY> rs.remove("gougou:27017") #移除成員
{
"ok" : 1,
"operationTime" : Timestamp(1546831380, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1546831380, 1),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
}

test:PRIMARY> rs.add("gougou:27017") #添加成員
{
"ok" : 1,
"operationTime" : Timestamp(1546831434, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1546831434, 1),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
}

test:PRIMARY> rs.conf() #查看副本集的優先級
{
"_id" : "test",
"version" : 4,
"protocolVersion" : NumberLong(1),
"writeConcernMajorityJournalDefault" : true,
"members" : [
{
"_id" : 0,
"host" : "zhuzhu:27017",
"arbiterOnly" : false,
"buildIndexes" : true,
"hidden" : false,
"priority" : 100,
"tags" : {

        },
        "slaveDelay" : NumberLong(0),
        "votes" : 1
    },
    {
        "_id" : 1,
        "host" : "gougou: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("5c2da4fc134c17137419c065")
}