【Mongodb】如何建立mongodb的replica set

標籤：monogodb centos

Replica sets 在主從複製上做的擴充，增加了故障自動切換和自動修複成員節點。下面從技術上介紹如何搭建mongodb的replica set (個人覺得，搭建mongodb本身沒有多少乾貨，重要是如何災難規劃)

1 建立複製叢集節點的資料存放目錄

mkdir -p /opt/mongodata/r1

mkdir -p /opt/mongodata/r2

mkdir -p /opt/mongodata/r3

2 在三個視窗分別執行如下命令：

./mongod --dbpath /opt/mongodata/r1 --port 27018  --rest --replSet myset

./mongod --dbpath /opt/mongodata/r2 --port 27019  --rest --replSet myset

./mongod --dbpath /opt/mongodata/r3 --port 27020  --rest --replSet myset

3 在第四個視窗執行如下命令：

[[email protected] bin]$ ./mongo 127.0.0.1:27018 init.js

MongoDB shell version: 2.0.1

connecting to: 127.0.0.1:27018/test

init.js 內容如下：

[[email protected] bin]$ cat init.js 

rs.initiate({

    _id : "myset",

    members : [

        {_id : 0, host : "10.250.7.220:27018"},

        {_id : 1, host : "10.250.7.220:27019"},

        {_id : 2, host : "10.250.7.220:27020"}

    ]

})

啟動3個服務節點，從log日誌可以看到，三個節點相互協商，選擇連接埠為27018的一個節點作為Primary，另外兩個自動作為Secondary節點。

Mon Oct 31 20:27:53 [conn2] replSet info saving a newer config version to local.system.replset

Mon Oct 31 20:27:53 [conn2] replSet saveConfigLocally done

Mon Oct 31 20:27:53 [conn2] replSet replSetInitiate config now saved locally.  Should come online in about a minute.

Mon Oct 31 20:27:53 [conn2] command admin.$cmd command: { replSetInitiate: { _id: "myset", members: [ { _id: 0.0, host: "10.250.7.220:27018" }, { _id: 1.0, host: "10.250.7.220:27019" }, { _id: 2.0, host: "10.250.7.220:27020" } ] } } ntoreturn:1 reslen:112 12095ms

Mon Oct 31 20:27:53 [conn2] end connection 127.0.0.1:15252

Mon Oct 31 20:27:53 [rsStart] replSet STARTUP2

Mon Oct 31 20:27:53 [rsHealthPoll] replSet info 10.250.7.220:27019 is down (or slow to respond): still initializing

Mon Oct 31 20:27:53 [rsHealthPoll] replSet member 10.250.7.220:27019 is now in state DOWN

Mon Oct 31 20:27:53 [rsHealthPoll] replSet info 10.250.7.220:27020 is down (or slow to respond): still initializing

Mon Oct 31 20:27:53 [rsHealthPoll] replSet member 10.250.7.220:27020 is now in state DOWN

Mon Oct 31 20:27:53 [rsSync] replSet SECONDARY

Mon Oct 31 20:27:55 [initandlisten] connection accepted from 10.250.7.220:44134 #3

Mon Oct 31 20:27:59 [rsHealthPoll] replSet info member 10.250.7.220:27019 is up

Mon Oct 31 20:27:59 [rsHealthPoll] replSet member 10.250.7.220:27019 is now in state STARTUP2

Mon Oct 31 20:27:59 [rsMgr] not electing self, 10.250.7.220:27019 would veto

Mon Oct 31 20:28:01 [initandlisten] connection accepted from 10.250.7.220:44137 #4

Mon Oct 31 20:28:05 [rsMgr] replSet info electSelf 0

Mon Oct 31 20:28:05 [rsMgr] replSet PRIMARY

Mon Oct 31 20:28:07 [rsHealthPoll] replSet member 10.250.7.220:27019 is now in state RECOVERING

Mon Oct 31 20:28:10 [initandlisten] connection accepted from 10.250.7.220:44141 #5

Mon Oct 31 20:28:10 [initandlisten] connection accepted from 10.250.7.220:44142 #6

Mon Oct 31 20:28:11 [slaveTracking] build index local.slaves { _id: 1 }

Mon Oct 31 20:28:11 [slaveTracking] build index done 0 records 0.001 secs

Mon Oct 31 20:28:13 [rsHealthPoll] replSet info member 10.250.7.220:27020 is up

Mon Oct 31 20:28:13 [rsHealthPoll] replSet member 10.250.7.220:27020 is now in state STARTUP2

Mon Oct 31 20:28:14 [conn6] end connection 10.250.7.220:44142

Mon Oct 31 20:28:14 [conn5] end connection 10.250.7.220:44141

Mon Oct 31 20:28:15 [initandlisten] connection accepted from 10.250.7.220:44144 #7

Mon Oct 31 20:28:15 [rsHealthPoll] replSet member 10.250.7.220:27019 is now in state SECONDARY

Mon Oct 31 20:28:15 [rsHealthPoll] replSet member 10.250.7.220:27020 is now in state RECOVERING

Mon Oct 31 20:28:28 [initandlisten] connection accepted from 127.0.0.1:59232 #8

從用戶端進入資料庫：

[[email protected] bin]$ ./mongo 127.0.0.1:27018

MongoDB shell version: 2.0.1

connecting to: 127.0.0.1:27018/test

PRIMARY> rs.status()  --查看replica set狀態的命令

{

        "set" : "myset",

        "date" : ISODate("2011-10-31T12:29:17Z"),

        "myState" : 1,

        "members" : [

                {

                        "_id" : 0,

                        "name" : "10.250.7.220:27018",

                        "health" : 1,

                        "state" : 1,

                        "stateStr" : "PRIMARY",

                        "optime" : {

                                "t" : 1320064073000,

                                "i" : 1

                        },

                        "optimeDate" : ISODate("2011-10-31T12:27:53Z"),

                        "self" : true

                },

                {

                        "_id" : 1,

                        "name" : "10.250.7.220:27019",

                        "health" : 1,

                        "state" : 2,

                        "stateStr" : "SECONDARY",

                        "uptime" : 78,

                        "optime" : {

                                "t" : 1320064073000,

                                "i" : 1

                        },

                        "optimeDate" : ISODate("2011-10-31T12:27:53Z"),

                        "lastHeartbeat" : ISODate("2011-10-31T12:29:16Z"),

                        "pingMs" : 0

                },

                {

                        "_id" : 2,

                        "name" : "10.250.7.220:27020",

                        "health" : 1,

                        "state" : 2,

                        "stateStr" : "SECONDARY",

                        "uptime" : 64,

                        "optime" : {

                                "t" : 1320064073000,

                                "i" : 1

                        },

                        "optimeDate" : ISODate("2011-10-31T12:27:53Z"),

                        "lastHeartbeat" : ISODate("2011-10-31T12:29:16Z"),

                        "pingMs" : 1

                }

        ],

        "ok" : 1

}

狀態中關鍵資料位元

state：1表示該host是當前可以進行讀寫，2：不能讀寫

health：1表示該host目前是正常的，0:異常

下面會進行從庫的讀測試，會出現error: { "$err" : "not master and slaveok=false", "code" : 13435 }

PRIMARY> rs.conf() --查看replica set配置的命令

{

        "_id" : "myset",

        "version" : 1,

        "members" : [

                {

                        "_id" : 0,

                        "host" : "10.250.7.220:27018"

                },

                {

                        "_id" : 1,

                        "host" : "10.250.7.220:27019"

                },

                {

                        "_id" : 2,

                        "host" : "10.250.7.220:27020"

                }

        ]

}

PRIMARY> db.isMaster();--查看是否是主庫的命令，當然可以從提示符中看出primary

{

        "setName" : "myset",

        "ismaster" : true,  ##是primary

        "secondary" : false,

        "hosts" : [

                "10.250.7.220:27018",

                "10.250.7.220:27020",

                "10.250.7.220:27019"

        ],

        "primary" : "10.250.7.220:27018",

        "me" : "10.250.7.220:27018",

        "maxBsonObjectSize" : 16777216,

        "ok" : 1

}

分別登入其他兩個mongodb 服務：

[[email protected] bin]$ ./mongo 127.0.0.1:27019

MongoDB shell version: 2.0.1

connecting to: 127.0.0.1:27019/test

SECONDARY> 

SECONDARY> 

SECONDARY> db.isMaster();

{

        "setName" : "myset",

        "ismaster" : false,

        "secondary" : true,

        "hosts" : [

                "10.250.7.220:27019",

                "10.250.7.220:27020",

                "10.250.7.220:27018"

        ],

        "primary" : "10.250.7.220:27018",

        "me" : "10.250.7.220:27019",

        "maxBsonObjectSize" : 16777216,

        "ok" : 1

}

SECONDARY>

[[email protected] bin]$ ./mongo 127.0.0.1:27020

MongoDB shell version: 2.0.1

connecting to: 127.0.0.1:27020/test

SECONDARY> 

SECONDARY> db.isMaster();

{

        "setName" : "myset",

        "ismaster" : false,

        "secondary" : true,

        "hosts" : [

                "10.250.7.220:27020",

                "10.250.7.220:27019",

                "10.250.7.220:27018"

        ],

        "primary" : "10.250.7.220:27018",

        "me" : "10.250.7.220:27020",

        "maxBsonObjectSize" : 16777216,

        "ok" : 1

} 

至此搭建成功。。

對主庫進行寫操作，從庫查看：

[[email protected] bin]$ ./mongo 127.0.0.1:27020

MongoDB shell version: 2.0.1

connecting to: 127.0.0.1:27020/test

PRIMARY> use test

switched to db test

PRIMARY> 

PRIMARY> db.yql.insert({val:"this is a message on 27020 primary !"});

PRIMARY> 

主庫日誌：

Mon Oct 31 21:03:46 [FileAllocator] allocating new datafile /opt/mongodata/r3/test.ns, filling with zeroes...

Mon Oct 31 21:03:46 [FileAllocator] done allocating datafile /opt/mongodata/r3/test.ns, size: 16MB,  took 0.256 secs

Mon Oct 31 21:03:46 [FileAllocator] allocating new datafile /opt/mongodata/r3/test.0, filling with zeroes...

Mon Oct 31 21:03:48 [clientcursormon] mem (MB) res:35 virt:2726 mapped:1248

Mon Oct 31 21:03:50 [FileAllocator] done allocating datafile /opt/mongodata/r3/test.0, size: 64MB,  took 4.488 secs

Mon Oct 31 21:03:50 [conn6] build index test.yql { _id: 1 }

Mon Oct 31 21:03:50 [conn6] build index done 0 records 0 secs

Mon Oct 31 21:03:50 [conn6] insert test.yql 4759ms

Mon Oct 31 21:03:50 [FileAllocator] allocating new datafile /opt/mongodata/r3/test.1, filling with zeroes...

Mon Oct 31 21:03:51 [conn8] getmore local.oplog.rs query: { ts: { $gte: new Date(5669632022159556609) } } cursorid:6257712144272734285 nreturned:1 reslen:146 5031ms

Mon Oct 31 21:03:51 [conn5] getmore local.oplog.rs query: { ts: { $gte: new Date(5669632022159556609) } } cursorid:423878080662643430 nreturned:1 reslen:146 5631ms

Mon Oct 31 21:03:54 [FileAllocator] done allocating datafile /opt/mongodata/r3/test.1, size: 128MB,  took 3.818 secs

從庫日誌，可以看出 從庫從主庫應用日誌，複製資料檔案的過程。

Mon Oct 31 20:49:27 [clientcursormon] mem (MB) res:19 virt:2693 mapped:1232

Mon Oct 31 20:54:27 [clientcursormon] mem (MB) res:19 virt:2693 mapped:1232

Mon Oct 31 20:59:27 [clientcursormon] mem (MB) res:19 virt:2693 mapped:1232

Mon Oct 31 21:03:51 [FileAllocator] allocating new datafile /opt/mongodata/r2/test.ns, filling with zeroes...

Mon Oct 31 21:03:54 [FileAllocator] done allocating datafile /opt/mongodata/r2/test.ns, size: 16MB,  took 3.396 secs

Mon Oct 31 21:03:54 [FileAllocator] allocating new datafile /opt/mongodata/r2/test.0, filling with zeroes...

Mon Oct 31 21:04:00 [FileAllocator] done allocating datafile /opt/mongodata/r2/test.0, size: 64MB,  took 5.79 secs

Mon Oct 31 21:04:00 [rsSync] build index test.yql { _id: 1 }

Mon Oct 31 21:04:00 [rsSync] build index done 0 records 0 secs

Mon Oct 31 21:04:00 [FileAllocator] allocating new datafile /opt/mongodata/r2/test.1, filling with zeroes...

Mon Oct 31 21:04:03 [FileAllocator] done allocating datafile /opt/mongodata/r2/test.1, size: 128MB,  took 2.965 secs

Mon Oct 31 21:04:37 [clientcursormon] mem (MB) res:17 virt:2853 mapped:1312

Mon Oct 31 21:04:41 [conn6] end connection 127.0.0.1:44672

如前面介紹rs.status()時所說，state：1表示該host是當前可以進行讀寫，2：不能讀寫

{

  "_id" : 1,

  "name" : "10.250.7.220:27019",

  "health" : 1,

  "state" : 2,  -- 從庫的state為 2 ，此時是不可讀寫的。

  "stateStr" : "SECONDARY",

  "uptime" : 78,

  "optime" : {

  "t" : 1320064073000,

  "i" : 1

 },

 在從庫進行讀操作，會報錯。

[[email protected] bin]$ ./mongo 127.0.0.1:27019

MongoDB shell version: 2.0.1

connecting to: 127.0.0.1:27019/test

SECONDARY> use test

switched to db test

SECONDARY> db.yql.find();

error: { "$err" : "not master and slaveok=false", "code" : 13435 }

本文出自 “夢想照進現實” 部落格，請務必保留此出處http://lookingdream.blog.51cto.com/5177800/1795016

【Mongodb】如何建立mongodb的replica set