資料庫Redis主從複製
阿新 • • 發佈：2019-01-04
工作原理
slave向master傳送sync命名---master啟動後臺存檔（收集所有修改資料命令）---完成後臺存檔後，傳送整個資料檔案到slave---slave接受資料檔案後，載入到記憶體，首次完成完全同步---有新的資料產生時，master繼續將新收集到的資料修改命令依次傳遞給slave，完成同步
缺點是網路或者系統繁忙，會產生資料同步延時問題
注：從庫不需要和主庫資料一致，配置完主從複製之後，從庫會自動同步資料並覆蓋自己的資料
從庫不作額外操作，客戶端只能在從庫上檢視資料，並不能寫入
結構模式
一主一從 一主多從 主從從
配置主從複製
| 拓 撲 結 構 |
|---|
| master伺服器 複製/同步 192.168.4.51/24 -------------------------------------------> 192.168.4.52/24 | | ---------------------------------------------------------------------------------------------- | clien 客戶機 192.168.4.50/24 |
配置從庫 進入redis 執行slaveof 主機IP 埠（這種配置是臨時的，重啟就失效了！）
永久配置，修改配置檔案/etc/redis/6379.conf 282 # slaveof <masterip> <masterport>
[[email protected] ~]# redis-cli -h 192.168.4.52 -p 6352
192.168.4.52:6352> SLAVEOF 192.168.4.51 6351
OK
192.168.4.52:6352> info replication //檢視主從配置資訊
# Replication
role:slave
master_host:192.168.4.51
master_port:6351
[[email protected] ~]# redis-cli -h 192.168.4.51 -p 6351
192.168.4.51:6351> info replication
# Replication
role:master
connected_slaves:1
slave0:ip=192.168.4.52,port=6352,state=online,offset=168,lag=1
master_replid:0c141f6f2be45cc6760898c0be1e2c16fc7f869e
192.168.4.51:6351> set x 123
OK
192.168.4.52:6352> keys * //在52上檢視資訊，已經同步
1) "x"
[[email protected] ~]# /etc/init.d/redis_6379 stop
[[email protected] ~]# vim /etc/redis/6379.conf
########### REPLICATION ###########
...
282 slaveof 192.168.4.51 6351
[[email protected] ~]# /etc/init.d/redis_6379 start
[[email protected] ~]# redis-cli -h 192.168.4.52 -p 6352
192.168.4.52:6352> info replication
# Replication
role:slave
master_host:192.168.4.51
master_port:6351
master_link_status:up
...
主庫宕機後，可以將從庫設定為主庫
命令列 slaveof no one 配置檔案在註釋掉（永久為主庫）
192.168.4.52:6352> slaveof no one
OK
192.168.4.52:6352> info replication
# Replication
role:master
配置帶驗證的主從配置
配置master主機，設定密碼
192.168.4.51:6351> shutdown
not connected> exit
[[email protected] ~]# vim /etc/redis/6379.conf
...
############# SECURITY #############
...
501 requirepass 123456
[[email protected] ~]# vim /etc/init.d/redis_6379
...
REDISPORT="6351 -h 192.168.4.51 -a 123456"
...
[[email protected] ~]# /etc/init.d/redis_6379 start
Starting Redis server...
[[email protected]~]# redis-cli -h 192.168.4.51 -p 6351
192.168.4.51:6351> keys *
(error) NOAUTH Authentication required. //需輸入密碼才可以檢視
192.168.4.51:6351> auth 123456
OK
192.168.4.51:6351> set y 123
配置 從庫主機，指定主庫IP，設定連結密碼（289 # masterauth <master-password>）
[[email protected] ~]# redis-cli -h 192.168.4.52 -p 6352
192.168.4.52:6352> INFO replication
# Replication
role:slave
master_host:192.168.4.51
master_port:6351
master_link_status:down //可以看到狀態已經關了
...
192.168.4.52:6352> keys * //資料也沒有同步
1) "x"
[[email protected] ~]# /etc/init.d/redis_6379 stop
[[email protected] ~]# vim /etc/redis/6379.conf
...
289 masterauth 123456
...
[[email protected] ~]# /etc/init.d/redis_6379 start
[[email protected] ~]# redis-cli -h 192.168.4.52 -p 6352
192.168.4.52:6352> INFO replication
# Replication
role:slave
master_host:192.168.4.51
master_port:6351
master_link_status:up
...
192.168.4.52:6352> keys *
1) "x"
2) "y"
配置一主兩從
在上面的基礎上新增53為51的從庫
[[email protected] ~]# /etc/init.d/redis_6379 stop
[[email protected] ~]# vim /etc/redis/6379.conf
...
############ REPLICATION ############
...
282 slaveof 192.168.4.51 6351
...
289 masterauth 123456
[[email protected] ~]# /etc/init.d/redis_6379 start
[[email protected] ~]# redis-cli -h 192.168.4.53 -p 6353
192.168.4.53:6353> info replication
# Replication
role:slave
master_host:192.168.4.51
master_port:6351
master_link_status:up
在51上驗證從庫，還有資料同步
[[email protected] ~]# redis-cli -h 192.168.4.51 -p 6351
192.168.4.51:6351> auth 123456
OK
192.168.4.51:6351> info replication
# Replication
role:master
connected_slaves:2
slave0:ip=192.168.4.52,port=6352,state=online,offset=1204,lag=0
slave1:ip=192.168.4.53,port=6353,state=online,offset=1204,lag=0
...
192.168.4.51:6351> set z 123
OK
在53上檢視資料是否同步
192.168.4.53:6353> keys *
1) "y"
2) "z"
3) "x"
客戶端連結主庫51，寫入資料，在53上再次檢視
[[email protected] ~]# redis-cli -h 192.168.4.51 -p 6351 -a 123456
192.168.4.51:6351> keys *
1) "y"
2) "x"
3) "z"
192.168.4.51:6351> set a 001
OK
[[email protected] ~]# redis-cli -h 192.168.4.53 -p 6353
192.168.4.53:6353> keys *
1) "y"
2) "a"
3) "z"
4) "x"
配置主從從結構
先將剛才用的從庫53還原為獨立的主庫
[[email protected] ~]# /etc/init.d/redis_6379 stop
[[email protected] ~]# vim /etc/redis/6379.conf
############## REPLICATION #############
...
282 #slaveof 192.168.4.51 6351 //註釋
...
289 #masterauth 123456 //註釋
[[email protected] ~]# /etc/init.d/redis_6379 start
[[email protected] ~]# redis-cli -h 192.168.4.53 -p 6353
192.168.4.53:6353> INFO replication
# Replication
role:master
192.168.4.53:6353> FLUSHALL
OK
192.168.4.53:6353> keys *
(empty list or set)修改配置檔案，設定為52的從庫
[[email protected] ~]# /etc/init.d/redis_6379 stop
[[email protected] ~]# vim /etc/redis/6379.conf
...
slaveof 192.168.4.52 6352
[[email protected] ~]# /etc/init.d/redis_6379 start
[[email protected] ~]# redis-cli -h 192.168.4.53 -p 6353
192.168.4.53:6353> info replication
# Replication
role:slave
master_host:192.168.4.52
master_port:6352
master_link_status:up
192.168.4.53:6353> keys *
1) "x"
2) "a"
3) "y"
4) "z"
客戶端連結51，並寫入資料，驗證從庫52和53
[[email protected] ~]# redis-cli -h 192.168.4.51 -p 6351 -a 123456
192.168.4.51:6351> set b 002
OK
192.168.4.52:6352> keys *
1) "y"
2) "z"
3) "a"
4) "b"
5) "x"
192.168.4.53:6353> keys *
1) "x"
2) "a"
3) "b"
4) "z"
5) "y"
哨兵（sentinel）模式 ----監控主庫
所用結構（主從從51 52 53）
編寫哨兵服務的配置檔案（在52上設定）
sentinel monitor <master-name> <ip> <redis-port> <quorum>
sentinel auth-pass <master-name> <password>
[[email protected] ~]# cd redis/redis-4.0.8/
[[email protected] redis-4.0.8]# cp sentinel.conf /etc/
[[email protected] redis-4.0.8]# vim /etc/sentinel.conf
...
15 bind 0.0.0.0
21 port 26379 //預設埠
...
52 # sentinel monitor <master-name> <ip> <redis-port> <quorum> //在下面新增
sentinel monitor redis51 192.168.4.51 6351 1
...
71 # sentinel auth-pass <master-name> <password> //在下面新增
sentinel auth-pass redis51 123456
...
啟動哨兵服務
[[email protected] ~]# redis-sentinel /etc/sentinel.conf
...
_.-``__ ''-._
_.-`` `. `_. ''-._ Redis 4.0.8 (00000000/0) 64 bit
.-`` .-```. ```\/ _.,_ ''-._
( ' , .-` | `, ) Running in sentinel mode
|`-._`-...-` __...-.``-._|'` _.-'| Port: 26379
| `-._ `._ / _.-' | PID: 3841
`-._ `-._ `-./ _.-' _.-'
|`-._`-._ `-.__.-' _.-'_.-'|
| `-._`-._ _.-'_.-' | http://redis.io
`-._ `-._`-.__.-'_.-' _.-'
|`-._`-._ `-.__.-' _.-'_.-'|
| `-._`-._ _.-'_.-' |
`-._ `-._`-.__.-'_.-' _.-'
`-._ `-.__.-' _.-'
`-._ _.-'
`-.__.-'
3841:X 24 Dec 11:55:57.666 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
3841:X 24 Dec 11:55:57.693 # Sentinel ID is 53ddd54e5bbba74e70927a758807995453a076ec
3841:X 24 Dec 11:55:57.694 # +monitor master mymaster 127.0.0.1 6379 quorum 2
3841:X 24 Dec 11:55:57.694 # +monitor master redis51 192.168.4.51 6351 quorum 1
3841:X 24 Dec 11:55:57.695 * +slave slave 192.168.4.52:6352 192.168.4.52 6352 @ redis51 192.168.4.51 6351
3841:X 24 Dec 11:56:27.674 # +sdown master mymaster 127.0.0.1 6379
[[email protected] ~]# redis-sentinel /etc/sentinel.conf & //可以放到後臺
測試（51宕機，52自動成為主庫）
[[email protected] ~]# redis-cli -h 192.168.4.51 -p 6351
192.168.4.51:6351> auth 123456
192.168.4.51:6351> shutdown
not connected>
[[email protected] ~]# redis-cli -h 192.168.4.52 -p 6352
192.168.4.52:6352> INFO replication
# Replication
role:master
connected_slaves:1
[[email protected] ~]# vim /etc/sentinel.conf //檔案的內容已經相應改變
# sentinel monitor <master-name> <ip> <redis-port> <quorum>
sentinel myid 53ddd54e5bbba74e70927a758807995453a076ec
...
# sentinel auth-pass <master-name> <password>
sentinel config-epoch mymaster 0
[[email protected] ~]# redis-sentinel /etc/sentinel.conf
...
3841:X 24 Dec 12:00:19.914 * +slave slave 192.168.4.53:6353 192.168.4.53 6353 @ redis51 192.168.4.52 6352
3841:X 24 Dec 12:00:49.023 # +sdown slave 192.168.4.51:6351 192.168.4.51 6351 @ redis51 192.168.4.52 6352
啟動51，自動成為52的從庫
[[email protected] ~]# /etc/init.d/redis_6379 start
[[email protected] ~]# redis-cli -h 192.168.4.52 -p 6352
192.168.4.52:6352> info replication
# Replication
role:master
connected_slaves:2
slave0:ip=192.168.4.53,port=6353,state=online,offset=573865,lag=1
slave1:ip=192.168.4.51,port=6351,state=online,offset=573865,lag=0
...