mongodb主從復制安裝文檔

• 環境說明

• mongodb下載與安裝

• 在10.240.216.151（主庫）上

# wget http://downloads.mongodb.org/linux/mongodb-linux-x86_64-2.0.4.tgz

（如果不能正常下載，可以直接從瀏覽器下載下來，然后傳到服務器上）

# tar -zxf mongodb-linux-x86_64-2.0.4.tgz-C /usr/local/

# mkdir -p /data/{db/geomaster/,log}

# touch /data/log/geomaster.log

# cd /usr/local/

# mv mongodb-linux-x86_64-2.0.4 mongodb

# /usr/local/mongodb/bin/mongod --fork--port 4000 --master --dbpath /data/db/geomaster/ --logpath /data/log/geomaster.log--logappend   啟動數據庫

# kill -2 `ps -ef |grep mongod |grep -vgrep |awk '{print $2}'`    關閉數據庫

• 在10.240.216.152 和 10.240.216.153（備庫）上

# wget http://downloads.mongodb.org/linux/mongodb-linux-x86_64-2.0.4.tgz

（如果不能正常下載，可以直接從瀏覽器下載下來，然后傳到服務器上）

# tar -zxf mongodb-linux-x86_64-2.0.4.tgz-C /usr/local/

# mkdir -p /data/{db/geoslave/,log}

# touch /data/log/geosalve.log

# cd /usr/local/

# mv mongodb-linux-x86_64-2.0.4 mongodb

# /usr/local/mongodb/bin/mongod --fork--port 4000 --slave --source 10.240.216.151:4000 --dbpath /data/db/geoslave/--logpath /data/log/geosalve.log --logappend --nojournal      啟動數據庫

# kill -2 `ps -ef |grep mongod |grep -vgrep |awk '{print $2}'`    關閉數據庫

• 驗證

• 在主庫上

# /usr/local/mongodb/bin/mongo127.0.0.1:4000

> db.runCommand ( {"isMaster": 1 } )

{ "ismaster" : true,"maxBsonObjectSize" : 16777216, "ok" : 1 }

• 在備庫上

# /usr/local/mongodb/bin/mongo127.0.0.1:4000

> db.runCommand ( {"isMaster": 1 } )

{

        "ismaster" : 0,

        "info" : "dead: data toostale halted replication",

        "maxBsonObjectSize" :16777216,

        "ok" : 1

}

> use local

switched to db local

> db.sources.find()

{ "_id" :ObjectId("55ebfa53ecf735439d6bafeb"), "host" :"10.240.216.151:4000", "source" : "main","syncedTo" : { "t" : 1441528400000, "i" : 1 } }

• 在主庫上創建庫和表以及添加一條數據

> use mydb

switched to db mydb

> db

mydb

>db.mydb.user.insert({"username":"zdh"});

> db.mydb.user.find();

{ "_id" :ObjectId("55ebfc2d92e237c3cb30ef9a"), "username" :"zdh" }

> show dbs;

local   6.2001953125GB

mydb    0.203125GB

• 在從庫上檢查數據同步情況

> show dbs;

local   0.203125GB

mydb    0.203125GB

> use mydb

switched to db mydb

> db.mydb.user.find()

{"_id" : ObjectId("55ebfc2d92e237c3cb30ef9a"),"username" : "zdh" }

以上輸出結果表示OK

對于上面這種master-slave結構有一個很重要的缺陷就是當主庫掛掉后，從庫要晉升為主庫時，需要手動做大量的工作才行，具體步驟有：

1. 停掉其中一臺slave，然后重新以master的身份啟動（晉升10.240.216.152為主庫）

# kill -2 `ps -ef |grep mongod |grep -vgrep |awk '{print $2}'`

# /usr/local/mongodb/bin/mongod --fork--port 4000 --master --dbpath /data/db/geoslave/ --logpath/data/log/geosalve.log –logappend

2. 如果不能找到研發修改代碼指向新的主庫IP，那么可以將原主庫關機并將其的IP切到新主庫服務器上（切IP場景，這種情況下slave端不需要重啟mongodb進程，此時原主庫將不能啟動，這是一個問題）

# ifconfig bond0:1 10.240.216.151 netmask255.255.255.0 up

# arping -I bond0 -c 3 -s 10.240.216.15110.240.216.254

3. 將從庫10.240.216.153指向新的主庫，需要先停掉mongodb，然后source指向新主庫啟動（在不切IP的情況下操作）

# kill -2 `ps -ef |grep mongod |grep -vgrep |awk '{print $2}'`

# rm -f /data/db/geoslave/mongod.lock /data/db/geoslave/local.*

# /usr/local/mongodb/bin/mongod --fork--port 4000 --slave --source 10.240.216.152:4000 --dbpath /data/db/geoslave/--logpath /data/log/geosalve.log --logappend –nojournal

# /usr/local/mongodb/bin/mongo127.0.0.1:4000

> use local

switched to db local

> db.sources.find()

{ "_id" :ObjectId("55ec04dadfd5d65f2f7fe404"), "host" :"10.240.216.152:4000", "source" : "main","syncedTo" : { "t" : 1441531234000, "i" : 1 } }

• 針對以上操作復雜的過程，我們作如下優化

• 在主庫10.240.216.151上執行

# /usr/local/mongodb/bin/mongod--fork --port 4000 --dbpath /data/db/geomaster/ --logpath/data/log/geomaster.log --logappend --master

• 在從庫（備主）10.240.216.152上執行

# /usr/local/mongodb/bin/mongod--fork --port 4000 --master --slave --dbpath /data/db/geoslave/ --logpath/data/log/geosalve.log –logappend

# /usr/local/mongodb/bin/mongo127.0.0.1:4000

> use local

switched to db local

> db.sources.find()

>db.sources.insert({"host":"10.240.216.151:4000"});

> db.sources.find()

{ "_id" :ObjectId("55ec120751fd14c6b2f23a18"), "host" :"10.240.216.151:4000" }

> db.sources.find()       隔30秒左右

{ "_id" :ObjectId("55ec120751fd14c6b2f23a18"), "host" :"10.240.216.151:4000", "source" : "main", "syncedTo": { "t" : 1441534596000, "i" : 1 } }

• 在從庫10.240.216.153上執行

#/usr/local/mongodb/bin/mongod --fork --port 4000 --slave  --dbpath /data/db/geomaster/ --logpath/data/log/geosalve.log --logappend –nojournal

# /usr/local/mongodb/bin/mongo127.0.0.1:4000

> use local

switched to db local

> db.sources.find()

>db.sources.insert({"host":"10.240.216.151:4000"})

>db.sources.insert({"host":"10.240.216.152:4000"})

> db.sources.find()

{ "_id" :ObjectId("55ec127a1924006f4e8b2e97"), "host" : "10.240.216.151:4000","source" : "main", "syncedTo" : { "t" :1441534586000, "i" : 1 } }

{ "_id" :ObjectId("55ec127e1924006f4e8b2e98"), "host" :"10.240.216.152:4000", "source" : "main","syncedTo" : { "t" : 1441534593000, "i" : 1 } }

以上配置完成。就實現了當主庫10.240.216.151掛掉后，備用主庫10.240.216.152可以直接提供對外的服務，無需重啟mongodb進程，并且從庫無需作任何更改。

• 驗證

• 在主庫10.240.216.151上

> show dbs

local   6.2001953125GB

mydb    0.203125GB

> use mydb

switched to db mydb

>db.mydb.user.insert({"username":"zhongguo","age":"26"})

> db.mydb.user.find()

{ "_id" :ObjectId("55ec12e4bab480b5485dd72e"), "username" :"zhongguo", "age" : "26" }

>db.mydb.user.insert({"username":"zhongguo2","age":"30"})

• 在從庫（備主）10.240.216.152上

> use mydb

switched to db mydb

> db.mydb.user.find()

{ "_id" :ObjectId("55ec12e4bab480b5485dd72e"), "username" :"zhongguo", "age" : "26" }

> db.mydb.user.insert({"username":"finished","time":"2015-09-06"})

> db.mydb.user.find()

{ "_id" : ObjectId("55ec12e4bab480b5485dd72e"),"username" : "zhongguo", "age" : "26" }

{ "_id" : ObjectId("55ec133e51fd14c6b2f23a19"),"username" : "finished", "time" :"2015-09-06" }

> db.mydb.user.find()

{ "_id" :ObjectId("55ec12e4bab480b5485dd72e"), "username" :"zhongguo", "age" : "26" }

{ "_id" :ObjectId("55ec133e51fd14c6b2f23a19"), "username" :"finished", "time" : "2015-09-06" }

{ "_id" :ObjectId("55ec136abab480b5485dd72f"), "username" :"zhongguo2", "age" : "30" }

• 在從庫10.240.216.153上

> use mydb

switched to db mydb

> db.mydb.user.find()

{ "_id" :ObjectId("55ec12e4bab480b5485dd72e"), "username" :"zhongguo", "age" : "26" }

> db.mydb.user.find()

{ "_id" : ObjectId("55ec12e4bab480b5485dd72e"),"username" : "zhongguo", "age" : "26" }

{ "_id" : ObjectId("55ec133e51fd14c6b2f23a19"),"username" : "finished", "time" :"2015-09-06" }

> db.mydb.user.find()

{ "_id" : ObjectId("55ec12e4bab480b5485dd72e"),"username" : "zhongguo", "age" : "26" }

{ "_id" :ObjectId("55ec133e51fd14c6b2f23a19"), "username" :"finished", "time" : "2015-09-06" }

{ "_id" :ObjectId("55ec136abab480b5485dd72f"), "username" :"zhongguo2", "age" : "30" }

上面的結果說明，備用從庫是即可生效的，需要保證的是我們的寫是確保從主庫上寫入的。