MongoDB 複製集管理

1.配置容許在從節點讀取數據

默認MongoDB 複製集的從節點不能讀取數據，能夠使用 rs.slaveOk()  命令容許可以在從節點讀取數據。

abc:PRIMARY> show dbs                         #在主節點上能夠讀取數據
admin   0.000GB
config  0.000GB
local   0.000GB
school  0.000GB
abc:PRIMARY> exit
bye
[root@localhost logs]# mongo --port 27018                        #進入端口爲27018 的從節點
MongoDB shell version v3.6.7
connecting to: mongodb://127.0.0.1:27018/
abc:SECONDARY> show dbs                                             #查看數據庫
2018-09-13T14:55:03.037+0800 E QUERY    [thread1] Error: listDatabases failed:{        #沒法讀取數據
     "operationTime" : Timestamp(1536821694, 1),
     "ok" : 0,
     "errmsg" : "not master and slaveOk=false",

    abc:SECONDARY> rs.slaveOk()                   #使用命令 rs.slaveOk() 命令容許可以在從節點讀取數據
abc:SECONDARY> show dbs
admin   0.000GB
config  0.000GB
local   0.000GB
school  0.000GB
abc:SECONDARY>

2.查看複製狀態信息

abc:SECONDARY> rs.help()

rs.printReplicationInfo()                  check oplog size and time range                               
rs.printSlaveReplicationInfo()             check replica set members and replication lag  

abc:SECONDARY> rs.printReplicationInfo()                                    #查看日誌大小和時間範圍
configured oplog size:   990MB
log length start to end: 3482secs (0.97hrs)
oplog first event time:  Thu Sep 13 2018 14:12:02 GMT+0800 (CST)
oplog last event time:   Thu Sep 13 2018 15:10:04 GMT+0800 (CST)
now:                     Thu Sep 13 2018 15:10:06 GMT+0800 (CST)
abc:SECONDARY> rs.printSlaveReplicationInfo()               #查看那些從節點複製數據                      
source: 192.168.213.184:27018
     syncedTo: Thu Sep 13 2018 15:11:54 GMT+0800 (CST)
     0 secs (0 hrs) behind the primary
source: 192.168.213.184:27019
     syncedTo: Thu Sep 13 2018 15:11:54 GMT+0800 (CST)
     0 secs (0 hrs) behind the primary

由此可看出仲裁節點並不具有數據複製

3. .更改oplog 大小

         oplog 即 opreations 的縮寫，存儲在 local 數據庫中。oplog 中新操做會自動替換舊的操做，以保證 oplog 不會超過預設的大小。默認狀況下。oplog 大小會佔用64位的實例5% 的磁盤空間。儘可能保證主節點的oplog 足夠大，可以存放至關長時間的操做記錄。

（1）首先關閉從節點服務器，從複製集中退出，暫時成爲單實例

abc:SECONDARY> use admin
switched to db admin

abc:SECONDARY> db.shutdownServer()                     #關閉服務
server should be down...

[root@localhost logs]# vim /etc/mongod2.conf              #更改實例2 的配置文件

port: 27028                                               #端口號更改

#replication:
#  replSetName: abc                             #註銷複製集

（2）以端口號爲 27028 進入數據庫

[root@localhost logs]# mongod -f /etc/mongod2.conf
about to fork child process, waiting until server is ready for connections.
forked process: 40575
child process started successfully, parent exiting
[root@localhost logs]# mongo --port 27028
MongoDB shell version v3.6.7
connecting to: mongodb://127.0.0.1:27028/

（3）對oplog 進行徹底備份

[root@localhost logs]# mongodump --port 27028 --db local --collection 'oplog.rs'
2018-09-13T15:30:19.876+0800    writing local.oplog.rs to
2018-09-13T15:30:19.881+0800    done dumping local.oplog.rs (376 documents)

（4）刪除原有的日誌文件

> use local
switched to db local
> show tables
me
oplog.rs
replset.election
replset.minvalid
replset.oplogTruncateAfterPoint
startup_log
system.replset
system.rollback.id
> db.oplog.rs.drop()
true
>  db.runCommand({create:"oplog.rs",capped:true,size:(2 * 1024 * 1024 * 1024)})        #原型建立 oplog.rs   指定大小
{ "ok" : 1 }
> use admin
switched to db admin
> db.shutdownServer()                      #關閉服務
server should be down...

（5）把獨立的實例 mongodb2 恢復到複製集，登陸。

> exit
bye
[root@localhost logs]# vim /etc/mongod2.conf          #把獨立的實例 mongodb2 恢復到複製集

port: 27018                      #把端口號改回爲27018

replication:                               #啓用複製集
   replSetName: abc
   oplogSizeMB: 2048              #指定 oplog 大小

[root@localhost logs]# mongod -f /etc/mongod2.conf
about to fork child process, waiting until server is ready for connections.
forked process: 40835
child process started successfully, parent exiting
[root@localhost logs]# mongo --port 27018
MongoDB shell version v3.6.7
connecting to: mongodb://127.0.0.1:27018/

abc:SECONDARY> rs.printReplicationInfo()    

configured oplog size:   2048MB
log length start to end: 90secs (0.03hrs)
oplog first event time:  Thu Sep 13 2018 15:44:15 GMT+0800 (CST)
oplog last event time:   Thu Sep 13 2018 15:45:45 GMT+0800 (CST)
now:                     Thu Sep 13 2018 15:45:54 GMT+0800 (CST)

4 .部署認證複製

（1）

abc:PRIMARY> use admin                    
switched to db admin

abc:PRIMARY> db.createUser({"user":"root","pwd":"123","roles":["root"]})    #建立用戶root  設置密碼爲 123
Successfully added user: { "user" : "root", "roles" : [ "root" ] }

（2）在每一個實例的配置文件中開啓認證功能

abc:PRIMARY> exit
bye
[root@localhost logs]# vim /etc/mongod.conf

security:
    keyFile: /usr/bin/abckey1                         #驗證文件路徑
    clusterAuthMode: keyFile                          #驗證模式，文件驗證

[root@localhost logs]# vim /etc/mongod2.conf

security:
    keyFile: /usr/bin/abckey2
    clusterAuthMode:keyFile

[root@localhost logs]# vim /etc/mongod3.conf

security:
    keyFile: /usr/bin/abckey3
    clusterAuthMode:keyFile

[root@localhost logs]# vim /etc/mongod4.conf

security:
    keyFile: /usr/bin/abckey4
    clusterAuthMode:keyFile

[root@localhost logs]# cd /usr/bin/
[root@localhost bin]# echo "abc key" > abckey1                 #生成4個密鑰文件
[root@localhost bin]# echo "abc key" > abckey2
[root@localhost bin]# echo "abc key" > abckey3
[root@localhost bin]# echo "abc key" > abckey4

（3）重啓4個實例

[root@localhost bin]# chmod 600 abc*              # 把文件 abc 權限設置爲600             
[root@localhost bin]# mongod -f /etc/mongod.conf                #啓動服務
about to fork child process, waiting until server is ready for connections.
forked process: 41828
child process started successfully, parent exiting
[root@localhost bin]# mongod -f /etc/mongod2.conf --shutdown
killing process with pid: 40835
[root@localhost bin]# mongod -f /etc/mongod2.conf
about to fork child process, waiting until server is ready for connections.
forked process: 42252
child process started successfully, parent exiting
[root@localhost bin]# mongod -f /etc/mongod3.conf --shutdown
killing process with pid: 4881
[root@localhost bin]# mongod -f /etc/mongod3.conf
about to fork child process, waiting until server is ready for connections.
forked process: 42451
child process started successfully, parent exiting
[root@localhost bin]# mongod -f /etc/mongod4.conf --shutdown
killing process with pid: 4909
[root@localhost bin]# mongod -f /etc/mongod4.conf
about to fork child process, waiting until server is ready for connections.
forked process: 42634
child process started successfully, parent exiting

（4）登陸主節點服務器驗證  

[root@localhost bin]# mongo --port 27018
MongoDB shell version v3.6.7
connecting to: mongodb://127.0.0.1:27018/
MongoDB server version: 3.6.7
abc:PRIMARY> show dbs                                          #在主節點查看數據庫
2018-09-13T16:49:14.542+0800 E QUERY    [thread1] Error: listDatabases failed:{           #沒法查詢
     "operationTime" : Timestamp(1536828545, 1),
     "ok" : 0,

abc:PRIMARY> rs.status()                #查看各節點狀態，也沒法查詢
{
     "operationTime" : Timestamp(1536828575, 1),
     "ok" : 0,
     "errmsg" : "not authorized on admin to execute command { replSetGetStatus: 1.0, $clusterTime: { clusterTime: Timestamp(1536828545, 1), signature: { hash: BinData(0, 40060B8D2AC8AC1AE68D47E9332835D2040120C2), keyId: 6600587920397041666 } }, $db: \"admin\" }",
     "code" : 13,
     "codeName" : "Unauthorized",
     "$clusterTime" : {
         "clusterTime" : Timestamp(1536828575, 1),
         "signature" : {
             "hash" : BinData(0,"gSi7raqiqfKJKSF42wlgu2rvggE="),
             "keyId" : NumberLong("6600587920397041666")
         }
     }
}

abc:PRIMARY> use admin               #進入admin 數據庫
switched to db admin
abc:PRIMARY> db.auth("root","123")           #進行身份驗證
1
abc:PRIMARY> show dbs                 #再查看數據庫
admin   0.000GB
config  0.000GB
local   0.000GB
school  0.000GB

（5）進入從節點服務器進行驗證

[root@localhost bin]# mongo --port 27019
MongoDB shell version v3.6.7
connecting to: mongodb://127.0.0.1:27019/
MongoDB server version: 3.6.7
abc:SECONDARY> show dbs                    #查看數據庫
2018-09-13T16:55:14.429+0800 E QUERY    [thread1] Error: listDatabases failed:{
     "operationTime" : Timestamp(1536828905, 1),
     "ok" : 0,

abc:SECONDARY> rs.slaveOk()

abc:SECONDARY> use admin                #進行身份驗證
switched to db admin
abc:SECONDARY> db.auth("root","123")
1

abc:SECONDARY> show dbs admin   0.000GB config  0.000GB local   0.000GB school  0.000GB