mongodb副本集原理

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replication:
oplogSizeMB: <int>
replSetName: <string>
secondaryIndexPrefetch: <string>
enableMajorityReadConcern: <boolean>

mongdb副本集中的成员:
primary: 负责写入数据
seconary: 负责同步主上的数据，提供读服务
仲裁节点： 不保有数据，不参与选主，只进行选主投票

副本集选举通过优先级，范围0-1000，0为仲裁节点，不参与选举。默认是1

如何设置？

MongoDB Enterprise shard-rs:PRIMARY> config=rs.conf()
MongoDB Enterprise shard-rs:PRIMARY> config
{
"_id" : "shard-rs",
"version" : 3,
"protocolVersion" : NumberLong(1),
"writeConcernMajorityJournalDefault" : true,
"members" : [
{
"_id" : 0,
"host" : "worker2:27020",
"arbiterOnly" : false,
"buildIndexes" : true,
"hidden" : false,
"priority" : 1,
"tags" : {

                    },
                    "slaveDelay" : NumberLong(0),
                    "votes" : 1
            },
            {
                    "_id" : 1,
                    "host" : "worker2:27021",
                    "arbiterOnly" : false,
                    "buildIndexes" : true,
                    "hidden" : false,
                    "priority" : 1,
                    "tags" : {

                    },
                    "slaveDelay" : NumberLong(0),
                    "votes" : 1
            },
            {
                    "_id" : 2,
                    "host" : "worker2:27022",
                    "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("5dd8bf958b8ea486b84c23b2")
    }

}

修改id值为2的分片优先级为3，当primary，则id值为2的成为prmary
config.members[2].priority=3

故意停掉27020进程
kill -9 82609

查看id值为2的主机是否成为primary
进入27022的mongdb：

MongoDB Enterprise shard-rs:PRIMARY> use admin
switched to db admin
MongoDB Enterprise shard-rs:PRIMARY> db.isMaster()
{
"hosts" : [
"worker2:27020",
"worker2:27021",
"worker2:27022"
],
"setName" : "shard-rs",
"setVersion" : 4,
"ismaster" : true, # 成为primary
"secondary" : false,

mongodb副本集原理

标签：写入   default   磁盘   switch   rtb   节点   adc   work   har   

原文地址：https://blog.51cto.com/9237101/2453447