Redis深刻系列-0x018：Redis同步實踐

時間 2019-11-15

標籤 redis 深刻系列 0x018 同步實踐欄目 Redis 简体版

原文原文鏈接

0x001 修改配置

複製兩份配置文件，分別命名爲redis_6378.conf、redis_6377.conf。他們將在6378、6377兩個端口啓動

分別修改兩個配置：redis

# redis_6378.conf
...
port 6378
slaveof 127.0.0.1 6379
...

# redis_6377.conf
...
port 6377
slaveof 127.0.0.1 6378
...

說明：這裏使用監聽6379的節點做爲主節點，6378做爲6379的子節點，6377做爲6378的子節點。shell

0x002 同步

啓動6379主節點socket

$ redis-server
68931:C 29 May 10:53:54.234 # oO0OoO0OoO0Oo Redis is starting                                 

# 省略部分過程
      _.-``    `.  `_.  ''-._           Redis 4.0.8 (00000000/0) 64 bit
  .-`` .-```.  ```\/    _.,_ ''-._                                   
 (    '      ,       .-`  | `,    )     Running in standalone mode
 |`-._`-...-` __...-.``-._|'` _.-'|     Port: 6379
 |    `-._   `._    /     _.-'    |     PID: 68931
# 省略部分過程
68931:M 29 May 10:53:54.237 * Ready to accept connections

啓動6378子節點code

$ redis-server ~/Desktop/redis_6378.conf 
# 省略部份內容
                _._                                                  
           _.-``__ ''-._                                             
      _.-``    `.  `_.  ''-._           Redis 4.0.8 (00000000/0) 64 bit
  .-`` .-```.  ```\/    _.,_ ''-._                                   
 (    '      ,       .-`  | `,    )     Running in standalone mode
 |`-._`-...-` __...-.``-._|'` _.-'|     Port: 6378
 |    `-._   `._    /     _.-'    |     PID: 69033

# 省略部份內容
# 這裏說明啓動成功了
69033:S 29 May 10:56:24.581 * Ready to accept connections
# 開始鏈接主節點
69033:S 29 May 10:56:24.581 * Connecting to MASTER 127.0.0.1:6379
# 開始同步
69033:S 29 May 10:56:24.581 * MASTER <-> SLAVE sync started
69033:S 29 May 10:56:24.581 * Non blocking connect for SYNC fired the event.
69033:S 29 May 10:56:24.581 * Master replied to PING, replication can continue...
# 嘗試增量同步
69033:S 29 May 10:56:24.581 * Trying a partial resynchronization (request 87953c7dc97cf1192a243fe5d7708c11acbd0e0f:1).
# 全量同步
69033:S 29 May 10:56:24.582 * Full resync from master: 98a56521a0a958295e499853621029d19ef6b357:0
69033:S 29 May 10:56:24.582 * Discarding previously cached master state.
69033:S 29 May 10:56:24.684 * MASTER <-> SLAVE sync: receiving 826 bytes from master
69033:S 29 May 10:56:24.685 * MASTER <-> SLAVE sync: Flushing old data
69033:S 29 May 10:56:24.685 * MASTER <-> SLAVE sync: Loading DB in memory
69033:S 29 May 10:56:24.685 * MASTER <-> SLAVE sync: Finished with success

此時的6379主節點server

# 省略部份內容
68931:M 29 May 10:53:54.237 * Ready to accept connections
# 上面是以前的狀態，下面是`6378`鏈接進來之後的狀態
68931:M 29 May 10:56:24.581 * Slave 127.0.0.1:6378 asks for synchronization
68931:M 29 May 10:56:24.581 * Partial resynchronization not accepted: Replication ID mismatch (Slave asked for '87953c7dc97cf1192a243fe5d7708c11acbd0e0f', my replication IDs are 'dbf6c826156fa5140d891996afcf8cc4f21b61fd' and '0000000000000000000000000000000000000000')
68931:M 29 May 10:56:24.581 * Starting BGSAVE for SYNC with target: disk
68931:M 29 May 10:56:24.582 * Background saving started by pid 69034
69034:C 29 May 10:56:24.584 * DB saved on disk
68931:M 29 May 10:56:24.684 * Background saving terminated with success
# 同步成功
68931:M 29 May 10:56:24.684 * Synchronization with slave 127.0.0.1:6378 succeeded

啓動6377子節點get

redis-server ~/Desktop/redis_6377.conf 
# 省略部份內容
                _._                                                  
           _.-``__ ''-._                                             
      _.-``    `.  `_.  ''-._           Redis 4.0.8 (00000000/0) 64 bit
  .-`` .-```.  ```\/    _.,_ ''-._                                   
 (    '      ,       .-`  | `,    )     Running in standalone mode
 |`-._`-...-` __...-.``-._|'` _.-'|     Port: 6377
 |    `-._   `._    /     _.-'    |     PID: 69207

# 啓動完成
69207:S 29 May 11:02:22.569 * Ready to accept connections
# 鏈接上一級節點
69207:S 29 May 11:02:22.569 * Connecting to MASTER 127.0.0.1:6378
69207:S 29 May 11:02:22.570 * MASTER <-> SLAVE sync started
69207:S 29 May 11:02:22.570 * Non blocking connect for SYNC fired the event.
69207:S 29 May 11:02:22.570 * Master replied to PING, replication can continue...
69207:S 29 May 11:02:22.570 * Trying a partial resynchronization (request 98a56521a0a958295e499853621029d19ef6b357:1).
69207:S 29 May 11:02:22.570 * Successful partial resynchronization with master.
69207:S 29 May 11:02:22.570 * MASTER <-> SLAVE sync: Master accepted a Partial Resynchronization.

0x003數據寫入

使用redis-cli向6379主節點寫入數據同步

$ redis-cli -h 127.0.0.1 -p 6379
127.0.0.1:6379> set name redis
OK
127.0.0.1:6379> get name
"redis"

使用redis-cli鏈接6378子節點並讀取在主節點寫入的數據it
```
$ redis-cli -h 127.0.0.1 -p 6378
127.0.0.1:6378> get name
"redis"
```
使用redis-cli鏈接637 7子節點並讀去在主節點寫入的數據io
```
$ redis-cli -h 127.0.0.1 -p 6377
127.0.0.1:6377> get name
"redis"
```

使用redis-cli鏈接6378子節點並嘗試寫入數據event

127.0.0.1:6378> set name redis-cli
(error) READONLY You can't write against a read only slave.

說明：子節點能夠讀取到主節點寫入的數據，說明同步成功了，子節點沒法寫入數據，由於子節點是默認只讀的，修改配置能夠作到子節點可讀寫

0x004 斷開鏈接

關閉6378子節點

$ redis-cli -h 127.0.0.1 -p 6378
127.0.0.1:6378> shutdown
not connected>

此時的6378

# 上面是以前的狀態，下面是`6378`關機時候的狀態
9033:S 29 May 11:09:54.587 # User requested shutdown...
69033:S 29 May 11:09:54.587 * Saving the final RDB snapshot before exiting.
69033:S 29 May 11:09:54.588 * DB saved on disk
69033:S 29 May 11:09:54.588 * Removing the pid file.
69033:S 29 May 11:09:54.589 # Redis is now ready to exit, bye bye...

此時的6379

# 上面是以前的狀態，下面是`6378`關機以後的狀態
68931:M 29 May 11:09:54.589 # Connection with slave 127.0.0.1:6378 lost.

此時的6377

...
# 6377 會一直嘗試從新鏈接`6378`
69219:S 29 May 11:12:07.132 * Connecting to MASTER 127.0.0.1:6378
69219:S 29 May 11:12:07.132 * MASTER <-> SLAVE sync started
69219:S 29 May 11:12:07.132 # Error condition on socket for SYNC: Connection refused
69219:S 29 May 11:12:07.132 * Connecting to MASTER 127.0.0.1:6378
69219:S 29 May 11:12:07.132 * MASTER <-> SLAVE sync started
69219:S 29 May 11:12:07.132 # Error condition on socket for SYNC: Connection refused
...

0x005 子節點可讀

修改配置
```
# redis_6378.conf
slave-read-only no
```

從新啓動6378，並向6378寫入數據

$ redis-cli -h 127.0.0.1 -p 6378
# 此時配置子節點不是隻讀的，因此能夠寫入
127.0.0.1:6378> set name redis-cli
OK
127.0.0.1:6378> get name 
"redis-cli"

鏈接6377並讀取6378寫入的key

$ redis-cli -h 127.0.0.1 -p 6377
127.0.0.1:6377> get name
"redis"

鏈接6379並讀取6378寫入的key

$ redis-cli -h 127.0.0.1 -p 6379
127.0.0.1:6379> GET name
"redis"

說明：雖然此時的6378子節點是可讀的，可是並不會傳播到其餘子節點或者主節點，而且在下次同步的時候，將會被刪除。

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