mongodb 3.4 学习 (三）复制集

复制集(replica set)

复制集是一组mongodb的进程维护同样的数据集，提供冗余与高可用性。最小的复制集由3台服务器（或者3个实例）组成，最多1个primary和2个secondary实例，其中只有primary允许读写，secondary只读。secondary和primary的数据完全一致，它们之间通过primary实例的oplog异步（asynchronous）方式同步数据。

oplog(operations log)是专门的capped collection，保存所有数据库相关修改的回滚记录，secondary成员通过异步的方式拷贝和执行这些操作。

当primary不可用时，复制集发起投票(elections),选择1台secondary做为primary，请注意priority这个参数，priority为0的secondary不能成为primary，不能触发投票。

Oplog Size

在Unix和Windows系统中, 如果存储引擎使用的是WiredTiger，将占用剩余使用空间的5%。

# 生产环境部署

kvm-70-101 10.0.70.101 # primary

kvm-70-102 10.0.70.102 # secondary

kvm-70-103 10.0.70.103 # secondary

# 生成key

openssl rand -base64 756 > mongodb_product_key

# 拷贝到所有成员服务器，并对文件授权

chmod 400 mongodb_product_key

chown mongod mongodb_product_key

# 变更/etc/mongod.conf，对复制集命名

security:

  keyFile: /etc/mongodb_product_key

replication:

  replSetName: myapp

# primary初始化

rs.initiate( {

   _id : 'myapp',

   members: [ { _id : 0, host : 'kvm-70-101:27017' },  { _id : 1, host : 'kvm-70-102:27017' },   { _id : 2, host : 'kvm-70-103:27017' } ]

})

{

    "info" : "try querying local.system.replset to see current configuration",

    "ok" : 0,

    "errmsg" : "already initialized",

    "code" : 23,

    "codeName" : "AlreadyInitialized"

}

# 建立超级用户admin

use admin

db.createUser(

  {

    user: 'admin',

    pwd: '@admin',

    roles: [ { role: 'root', db: 'admin' } ]

  }

);

# 建立app数据库的管理员app

use app

db.createUser(

  {

    user: 'app',

    pwd: '@app',

    roles: [ { role: 'dbOwner', db: 'app' } ]

  }

);

# 认证登录

db.auth('admin', '@admin')

# 如果另外增加secondary，使用以下命令

rs.add('kvm-70-104:27017')

rs.add('kvm-70-104:27017')

# 查看配置

rs.conf()

{

    "_id" : "myapp",

    "version" : 3,

    "protocolVersion" : NumberLong(1),

    "members" : [

        {

            "_id" : 0,

            "host" : "kvm-70-101:27017",

            "arbiterOnly" : false,

            "buildIndexes" : true,

            "hidden" : false,

            "priority" : 1,

            "tags" : {

            },

            "slaveDelay" : NumberLong(0),

            "votes" : 1

        },

        {

            "_id" : 1,

            "host" : "kvm-70-102:27017",

            "arbiterOnly" : false,

            "buildIndexes" : true,

            "hidden" : false,

            "priority" : 1,

            "tags" : {

            },

            "slaveDelay" : NumberLong(0),

            "votes" : 1

        },

        {

            "_id" : 2,

            "host" : kvm-70-103:27017",

            "arbiterOnly" : false,

            "buildIndexes" : true,

            "hidden" : false,

            "priority" : 1,

            "tags" : {

            },

            "slaveDelay" : NumberLong(0),

            "votes" : 1

        }

    ],

    "settings" : {

        "chainingAllowed" : true,

        "heartbeatIntervalMillis" : 2000,

        "heartbeatTimeoutSecs" : 10,

        "electionTimeoutMillis" : 10000,

        "catchUpTimeoutMillis" : 2000,

        "getLastErrorModes" : {

        },

        "getLastErrorDefaults" : {

            "w" : 1,

            "wtimeout" : 0

        },

        "replicaSetId" : ObjectId("59248e52d45510744805fb78")

    }

}

# 查看状态

 rs.status()

{

    "set" : "myapp",

    "date" : ISODate("2017-05-23T20:37:08.946Z"),

    "myState" : 1,

    "term" : NumberLong(1),

    "heartbeatIntervalMillis" : NumberLong(2000),

    "optimes" : {

        "lastCommittedOpTime" : {

            "ts" : Timestamp(1495571827, 1),

            "t" : NumberLong(1)

        },

        "appliedOpTime" : {

            "ts" : Timestamp(1495571827, 1),

            "t" : NumberLong(1)

        },

        "durableOpTime" : {

            "ts" : Timestamp(1495571827, 1),

            "t" : NumberLong(1)

        }

    },

    "members" : [

        {

            "_id" : 0,

            "name" : "kvm-70-101:27017",

            "health" : 1,

            "state" : 1,

            "stateStr" : "PRIMARY",

            "uptime" : 4968,

            "optime" : {

                "ts" : Timestamp(1495571827, 1),

                "t" : NumberLong(1)

            },

            "optimeDate" : ISODate("2017-05-23T20:37:07Z"),

            "electionTime" : Timestamp(1495567955, 2),

            "electionDate" : ISODate("2017-05-23T19:32:35Z"),

            "configVersion" : 3,

            "self" : true

        },

        {

            "_id" : 1,

            "name" : "kvm-70-102:27017",

            "health" : 1,

            "state" : 2,

            "stateStr" : "SECONDARY",

            "uptime" : 77,

            "optime" : {

                "ts" : Timestamp(1495571827, 1),

                "t" : NumberLong(1)

            },

            "optimeDurable" : {

                "ts" : Timestamp(1495571827, 1),

                "t" : NumberLong(1)

            },

            "optimeDate" : ISODate("2017-05-23T20:37:07Z"),

            "optimeDurableDate" : ISODate("2017-05-23T20:37:07Z"),

            "lastHeartbeat" : ISODate("2017-05-23T20:37:07.702Z"),

            "lastHeartbeatRecv" : ISODate("2017-05-23T20:37:06.951Z"),

            "pingMs" : NumberLong(0),

            "syncingTo" : "10.0.70.103:27017",

            "configVersion" : 3

        },

        {

            "_id" : 2,

            "name" : "kvm-70-103:27017",

            "health" : 1,

            "state" : 2,

            "stateStr" : "SECONDARY",

            "uptime" : 77,

            "optime" : {

                "ts" : Timestamp(1495571827, 1),

                "t" : NumberLong(1)

            },

            "optimeDurable" : {

                "ts" : Timestamp(1495571827, 1),

                "t" : NumberLong(1)

            },

            "optimeDate" : ISODate("2017-05-23T20:37:07Z"),

            "optimeDurableDate" : ISODate("2017-05-23T20:37:07Z"),

            "lastHeartbeat" : ISODate("2017-05-23T20:37:07.708Z"),

            "lastHeartbeatRecv" : ISODate("2017-05-23T20:37:07.733Z"),

            "pingMs" : NumberLong(0),

            "syncingTo" : "10.0.70.101:27017",

            "configVersion" : 3

        }

    ],

    "ok" : 1

}

# secondary验证

# 授权从机允许读

rs.slaveOk()

use app

db.auth('app', '@app')

db.test.insert({'hello': 'world'})

# 查看建立的数据库及用户

rs0:SECONDARY> db.test.find().pretty();

{ "_id" : ObjectId("5ad6c7e574a09792011db5ee"), "hello" : "world" }

# 进行一次新的投票

rs.stepDown()

巴特西

mongodb 3.4 学习 (三）复制集

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