簡介：
mongodb有兩種類型的複製，第一種是同於MySQL的主從複製模式，第二種是複製集，提供了自動故障轉移的主從複製集羣。其中複製集沒有固定的主節點，當一個主機的故障後從節點會重新“選舉”出一個新的主節點，從而提高的系統的可用性
一、實驗環境：
(1)各節點信息：
node1： 172.16.2.12
node2： 172.16.2.13
node3： 172.16.2.14
(2)各個節點之間確保時間同步
(3)各個節點確保iptables和selinux以關閉
二、在配置複製集時我們需要了解複製集的影響因素
(1)複製集(副本集）重新選舉的影響條件
心跳信息(heartbeat)、優先級(priority)、optime(某成員節點最近一次應用本地oplog的時間戳)、網絡連接、網絡分區
(2)觸發選舉的事件：
①新副本集初始化；
②從節點聯繫不到主節點；
③主節點"下臺"時；有以下原因會導致主節點"下臺"
主節點收到setupDown()命令時會下臺；
某從節點有更高的優先級且已經滿足成爲主節點的其他所有條件；
主節點無法聯繫到副本集的"多數方"
三、配置過程
(1)各個節點安裝mongodb
[mongodb-org-2.6] \\準備yum源 name=MongoDB 2.6 Repository baseurl=http://downloads-distro.mongodb.org/repo/redhat/os/x86_64/ gpgcheck=0 enabled=1
# yum -y install mongodb-org-server mongodb-org-shell mongodb-org-tools \\每個節點都要安裝
(2)創建mongodb數據存放目錄
# mkdir -vp /mongodb/data; chown -R mongod.mongod /mongodb \\每個節點都要創建，方法相同
(3)編輯mongodb配置文件：/etc/mongod.conf，修改內容如下：
[root@node1 ~]# cat /etc/mongod.conf # mongod.conf #where to log logpath=/var/log/mongodb/mongod.log \\指定log日誌文件路徑 logappend=true \\是否自動切割日誌 # fork and run in background fork=true \\是否在後端運行 #port=27017 \\指定監聽端口；默認即可 dbpath=/mongodb/data \\指定數據存放路徑 # location of pidfile pidfilepath=/var/run/mongodb/mongod.pid \\指明pid文件路徑 # Listen to local interface only. Comment out to listen on all interfaces. #bind_ip=127.0.0.1 \\指定監聽端口，默認爲127.0.0.1,最好根據實際需求定義 # Disables write-ahead journaling # nojournal=true # Enables periodic logging of CPU utilization and I/O wait #cpu=true # Turn on/off security. Off is currently the default #noauth=true #auth=true # Verbose logging output. #verbose=true # Inspect all client data for validity on receipt (useful for # developing drivers) #objcheck=true # Enable db quota management #quota=true # Set oplogging level where n is # 0=off (default) # 1=W # 2=R # 3=both # 7=W+some reads #diaglog=0 # Ignore query hints #nohints=true # Enable the HTTP interface (Defaults to port 28017). #httpinterface=true #rest=true # Turns off server-side scripting. This will result in greatly limited # functionality #noscripting=true # Turns off table scans. Any query that would do a table scan fails. #notablescan=true # Disable data file preallocation. #noprealloc=true # Specify .ns file size for new databases. # nssize=<size> # Replication Options # in replicated mongo databases, specify the replica set name here replSet=one \\最重要的一項，設置複製集的名稱，這裏設置爲“one” replIndexPrefetch=_id_only \\這裏設置取回的索引，此次設置的是"_id_only" # maximum size in megabytes for replication operation log #oplogSize=1024 # path to a key file storing authentication info for connections # between replica set members #keyFile=/path/to/keyfile
[root@node1 ~]# scp /etc/mongod.conf node2:/etc/ \\複製配置文件給node2節點一份 [root@node1 ~]# scp /etc/mongod.conf node3:/etc/ \\複製配置文件給node3節點一份 [root@node1 ~]# /etc/init.d/mongod start Starting mongod: [ OK ] [root@node2 ~]# /etc/init.d/mongod start Starting mongod: [ OK ] [root@node3 ~]# /etc/init.d/mongod start Starting mongod: [ OK ]
(4)配置主節點
[root@node1 ~]# mongo \\登錄到mongodb數據庫
MongoDB shell version: 2.6.11
connecting to: test
Welcome to the MongoDB shell.
For interactive help, type "help".
For more comprehensive documentation, see
http://docs.mongodb.org/
Questions? Try the support group
http://groups.google.com/group/mongodb-user
> rs.initiate() \\初始化複製集
{
"info2" : "no configuration explicitly specified -- making one",
"me" : "node1.linux.com:27017",
"info" : "Config now saved locally. Should come online in about a minute.",
"ok" : 1
}
>
one:PRIMARY> \\初始化複製集後，提示符變成現在的樣子
one:PRIMARY> rs.add("172.16.2.13") \\添加node2從節點
{ "ok" : 1 }
one:PRIMARY> rs.add("172.16.2.14") \\添加node3從節點
{ "ok" : 1(5)配置從節點
[root@node2 ~]# mongo \\鏈接node2節點的mongodb MongoDB shell version: 2.6.11 connecting to: test one:SECONDARY> rs.slaveOk() \\啓動node2從節點 [root@node3 ~]# mongo \\鏈接node2節點的mongodb MongoDB shell version: 2.6.11 connecting to: test one:SECONDARY> rs.slaveOk() \\啓動node3從節點
(6)查看各個節點信息：
one:PRIMARY> rs.status()
{
"set" : "one", \\“one”複製集的名稱
"date" : ISODate("2015-08-29T08:59:14Z"), \\日期類型
"myState" : 1, \\當前狀態
"members" : [ \\複製集成員信息
{
"_id" : 0, \\主節點ID
"name" : "node1.linux.com:27017", \\主節點的主機名
"health" : 1, \\節點健康值
"state" : 1, \\狀態
"stateStr" : "PRIMARY", \\當前爲主節點
"uptime" : 848, \\運行時長
"optime" : Timestamp(1440838386, 1), \\時間戳
"optimeDate" : ISODate("2015-08-29T08:53:06Z"),
"electionTime" : Timestamp(1440838311, 2),
"electionDate" : ISODate("2015-08-29T08:51:51Z"),
"self" : true \\如果在當前主機則爲true，否則爲false
},
{
"_id" : 1,
"name" : "172.16.2.13:27017",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 372,
"optime" : Timestamp(1440838386, 1),
"optimeDate" : ISODate("2015-08-29T08:53:06Z"),
"lastHeartbeat" : ISODate("2015-08-29T08:59:12Z"),
"lastHeartbeatRecv" : ISODate("2015-08-29T08:59:13Z"),
"pingMs" : 1,
"syncingTo" : "node1.linux.com:27017" \\從那臺主機同步數據
},
{
"_id" : 2,
"name" : "172.16.2.14:27017",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 368,
"optime" : Timestamp(1440838386, 1),
"optimeDate" : ISODate("2015-08-29T08:53:06Z"),
"lastHeartbeat" : ISODate("2015-08-29T08:59:13Z"),
"lastHeartbeatRecv" : ISODate("2015-08-29T08:59:14Z"),
"pingMs" : 1,
"syncingTo" : "node1.linux.com:27017"
}
],
"ok" : 1
}(7)驗證複製集節點數據是否同步
one:PRIMARY> use testdb \\切換到新的數據庫；
switched to db testdb
one:PRIMARY> for(i=1;i<=100;i++) db.test.insert({name: "stu"+i, age: "i%100", class: "Net12"})
\\在主節點插入數據
one:SECONDARY> db.test.find() \\在node2從節點查看主節點插入的數據
{ "_id" : ObjectId("55e177388aa7580730a33942"), "name" : "stu1", "age" : "i%100", "class" : "Net12" }
{ "_id" : ObjectId("55e177388aa7580730a33943"), "name" : "stu2", "age" : "i%100", "class" : "Net12" }
{ "_id" : ObjectId("55e177388aa7580730a33944"), "name" : "stu3", "age" : "i%100", "class" : "Net12" }
{ "_id" : ObjectId("55e177388aa7580730a33945"), "name" : "stu4", "age" : "i%100", "class" : "Net12"
}
one:SECONDARY> db.test.find() \\在node3節點查看主節點插入的數據
{ "_id" : ObjectId("55e177388aa7580730a33942"), "name" : "stu1", "age" : "i%100", "class" : "Net12" }
{ "_id" : ObjectId("55e177388aa7580730a33943"), "name" : "stu2", "age" : "i%100", "class" : "Net12" }
{ "_id" : ObjectId("55e177388aa7580730a33944"), "name" : "stu3", "age" : "i%100", "class" : "Net12" }
{ "_id" : ObjectId("55e177388aa7580730a33945"), "name" : "stu4", "age" : "i%100", "class" : "Net12" }
{ "_id" : ObjectId("55e177388aa7580730a33946"), "name" : "stu5", "age" : "i%100", "class" : "Net12" }
{ "_id" : ObjectId("55e177388aa7580730a33947"), "name" : "stu6", "age" : "i%100", "class" : "Net12" }
{ "_id" : ObjectId("55e177388aa7580730a33948"), "name" : "stu7", "age" : "i%100", "class" : "Net12" }(8)驗證從節點是否可以寫入數據
one:SECONDARY> db.test.insert({name: "stu101", age: 20, class: "Net12"})\\在node2測試，從節不能寫入
WriteResult({ "writeError" : { "code" : undefined, "errmsg" : "not master" } })
one:SECONDARY> db.test.insert({name: "stu101", age: 20, class: "Net12"})\\在node3測試，從節點不能寫入
WriteResult({ "writeError" : { "code" : undefined, "errmsg" : "not master" } })(9)通過以上測試，可以證明mongodb的複製集已經可以正常工作同時從節點只有讀權限，而主節點有讀寫權限
(10)mongodb額外命令可以通過rs.help()查看幫助信息，下面只介紹常用的幾個命令
one:PRIMARY> rs.printReplicationInfo() \\打印出複製集信息 configured oplog size: 1301.37744140625MB log length start to end: 1169secs (0.32hrs) oplog first event time: Sat Aug 29 2015 16:51:51 GMT+0800 (CST) oplog last event time: Sat Aug 29 2015 17:11:20 GMT+0800 (CST) now: Sat Aug 29 2015 17:19:35 GMT+0800 (CST) one:PRIMARY> rs.printSlaveReplicationInfo() \\查看主從複製延遲 source: 172.16.2.13:27017 syncedTo: Sat Aug 29 2015 17:11:20 GMT+0800 (CST) 0 secs (0 hrs) behind the primary source: 172.16.2.14:27017 syncedTo: Sat Aug 29 2015 17:11:20 GMT+0800 (CST) 0 secs (0 hrs) behind the primary one:PRIMARY>
謝謝大家花時間看完我寫的博客，若有不足支持請多多提出寶貴的意見。O(∩_∩)O
轉載請註明：linux運維部落 mongodb的複製集實現