Related operations of Redis master-slave synchronization and read-write separation settings

This article introduces the use of the master-slave synchronization function (master, slave) of Redis to enable the program to separate reading and writing, avoid io bottlenecks, and improve data reading and writing efficiency.

Redis supports one master server to synchronize multiple slave servers, and the synchronization uses the publish/subscribe mechanism.
One master can also be layered for multiple slaves. Each slave can synchronize the slave again and expand it into a tree structure.

Redis master-slave synchronization setting

The default port of Redis is 6379. In order not to affect the original Redis, we use the new port

master Configurationredis_master.conf

port 6300requirepass 123456masterauth 123456daemonize yes

slave1 Configurationredis_slave1.conf Set as master’s slave

port 6301slaveof 127.0.0.1 6300requirepass 123456masterauth 123456daemonize yes

slave2 Configurationredis_slave2.conf Set slave

port 6302slaveof 127.0.0.1 6300requirepass 123456masterauth 123456daemonize yes

daemonize to the master to indicate background startup.
requirepass Password for host authentication.
masterauth Verify the password for the slave to access the host, which needs to be consistent with the host's requirepass.
Since master-slave switching needs to be demonstrated later, the verification passwords of the three sets of conf are the same.

Redis master-slave synchronization test

Start master, slave1, slave2 in sequence

redis-server redis_master.conf
redis-server redis_slave1.conf
redis-server redis_slave2.conf

After execution, check whether the startup is successful

ps aux|grep redis
root  1858  Ss  3:55  0:00.01 redis-server *:6302 root  1849  Ss  3:54  0:00.01 redis-server *:6301 root  1842  Ss  3:54  0:00.02 redis-server *:6300

Entermaster, set the value of key abc to 123

redis-cli -p 6300127.0.0.1:6300> auth 123456OK127.0.0.1:6300> set abc 123OK127.0.0.1:6300> get abc"123"

Enter slave1 and slave2 respectively to check whether the data is synchronized
slave1:

redis-cli -p 6301
127.0.0.1:6301> auth 123456OK127.0.0.1:6301> get abc"123"
127.0.0.1:6301>

slave2:

redis-cli -p 6302
127.0.0.1:6302> auth 123456OK127.0.0.1:6302> get abc"123"
127.0.0.1:6302>

EntermasterModify the value of key abc to 456

127.0.0.1:6300> set abc 456OK127.0.0.1:6300> get abc"456"

Check whether slave1 and slave2 are synchronized
slave1:

127.0.0.1:6301> get abc"456"

slave2:

127.0.0.1:6302> get abc"456"

Redis master-slave switching

During the operation process, if there is a problem with the master, we can set up another slave The machine is automatically set to master. The sentinel function of Redis is mainly used here to implement master-slave switching.

sentinel1.conf

port 26301sentinel monitor master 127.0.0.1 6300 2sentinel auth-pass master 123456logfile "/tmp/sentinel.log"daemonize yes

sentinel2.conf

port 26302sentinel monitor master 127.0.0.1 6300 2sentinel auth-pass master 123456logfile "/tmp/sentinel.log"daemonize yes

sentinel monitor master 127.0.0.1 6300 2# The 2 in ## indicates that master-slave switching will be performed only when more than 2 sentinel services detect master failure.

Start two sentinel processes

redis-server sentinel1.conf --sentinel
redis-server sentinel2.conf --sentinel
ps aux|grep redis
root  2643  Ss  4:28 0:00.02 redis-server *:26302 [sentinel]  
root  2636  Ss  4:28 0:00.02 redis-server *:26301 [sentinel]

Redis log can be seen, the startup is successful and start monitoring

Running mode=sentinel, port=26301.
Sentinel ID is 3a23343948cd7f26662ccba1d01b92955311ef52
+monitor master master 127.0.0.1 6300 quorum 2+slave slave 127.0.0.1:6301 127.0.0.1 6301 @ master 127.0.0.1 6300+slave slave 127.0.0.1:6302 127.0.0.1 6302 @ master 127.0.0.1 6300Running mode=sentinel, port=26302.
Sentinel ID is ce0ee2af6b454205a3e475763945f505a10a7d6a
+monitor master master 127.0.0.1 6300 quorum 2+slave slave 127.0.0.1:6301 127.0.0.1 6301 @ master 127.0.0.1 6300+slave slave 127.0.0.1:6302 127.0.0.1 6302 @ master 127.0.0.1 6300+sentinel sentinel 3a23343948cd7f26662ccba1d01b92955311ef52 127.0.0.1 26301 @ master 127.0.0.1 6300+sentinel sentinel ce0ee2af6b454205a3e475763945f505a10a7d6a 127.0.0.1 26302 @ master 127.0.0.1 6300

Terminate the master, test the master and slave After switching the

kill master process, sentinel determines that the master is invalid and performs master-slave switching processing.

The log is as follows:

+failover-state-reconf-slaves master master 127.0.0.1 6300+slave-reconf-sent slave 127.0.0.1:6301 127.0.0.1 6301 @ master 127.0.0.1 6300+config-update-from sentinel 3a23343948cd7f26662ccba1d01b92955311ef52 127.0.0.1 26301 +switch-master master 127.0.0.1 6300 127.0.0.1 6302+slave slave 127.0.0.1:6301 127.0.0.1 6301 @ master 127.0.0.1 6302+slave slave 127.0.0.1:6300 127.0.0.1 6300 @ master 127.0.0.1 6302-odown master master 127.0.0.1 6300+slave-reconf-inprog slave 127.0.0.1:6301 127.0.0.1 6301 @ master 127.0.0.1 6300+slave-reconf-done slave 127.0.0.1:6301 127.0.0.1 6301 @ master 127.0.0.1 6300+failover-end master master 127.0.0.1 6300+switch-master master 127.0.0.1 6300 127.0.0.1 6302+convert-to-slave slave 127.0.0.1:6300 127.0.0.1 6300 @ master 127.0.0.1 6302

As can be seen from the log, the master-slave switch performed the following operations:

1. Switch

slave2 For the new master, slaveof 127.0.0.1 6300 in redis_slave2.conf is automatically deleted.

2. Automatically update slaveof 127.0.0.1 6300 in redis_slave1.conf to slaveof 127.0.0.1 6302, and use slave2 as the new master.

3.

After the original master is restarted, it will be used as a slave, and slaveof 127.0.0.1 6302 will be added to redis_master.conf automatically.

Conduct master-slave synchronization test after restarting the original master

Original masterUpdate key abc to 888, because it is now a slave. So the update failed.

127.0.0.1:6300> set abc 888(error) READONLY You can't write against a read only slave.

slave2 Update key abc to 888

127.0.0.1:6302> set abc 888OK127.0.0.1:6302> get abc"888"

Original master, slave1 checks whether it is synchronized

Original master

127.0.0.1:6300> get abc"888"

slave1

127.0.0.1:6301> get abc"888"

After inspection, after the master-slave switch, slave2 serves as the new master and other servers serve as slaves and can be used normally.

This article explains the related operations of Redis master-slave synchronization and read-write separation settings. For more related content, please pay attention to the PHP Chinese website.

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