Detailed explanation of the master-slave replication function of Redis

Redis is an open source memory-based key-value storage system, commonly used in scenarios such as caching, queuing, and real-time data processing. In large-scale applications, in order to improve the availability and performance of Redis, it is often necessary to adopt a distributed architecture, in which master-slave replication is a commonly used mechanism.

This article will introduce the master-slave replication function of Redis, including definition, principle, configuration and application scenarios.

1. Definition

The master-slave replication of Redis refers to automatically synchronizing the data of one Redis node (ie the master node) to other nodes (ie the slave node) to achieve data replication and load balanced purpose. The master node is responsible for write operations, and the slave node is responsible for read operations; when the master node fails, the slave node can take over from the master node and continue running, thereby improving the availability and fault tolerance of Redis.

2. Principle

Redis’ master-slave replication is based on the asynchronous replication mechanism. When the master node receives a write operation, it will encapsulate the write command into an RDB file or AOF file, save it to the disk, and execute it in memory. At the same time, the master node broadcasts the write command to all slave nodes to achieve synchronous update of data.

After receiving the broadcast command from the master node, the slave node will parse and execute the command, and reply the execution result to the master node. The master node will confirm or resend based on the feedback from the slave node.

Since master-slave replication is based on an asynchronous replication mechanism, there is a data delay to a certain extent, that is, the data of the slave node is not necessarily exactly the same as the data of the master node. In addition, when the master node fails, data inconsistency and loss may occur.

3. Configuration

Redis’ master-slave replication requires relevant configuration, including the startup parameters and configuration files of the master node and slave node, etc.

1. Master node configuration

The master node needs to set the following parameters in the configuration file:

# 设置节点的名称为“mymaster”
slaveof no one
port 6379
pidfile /var/run/redis/redis-server.pid
logfile /var/log/redis/redis-server.log

2. Slave node configuration

The slave node needs to set the following parameters in the configuration file:

# 设置节点的名称为“myslave”
slaveof mymaster 6379
port 6380
pidfile /var/run/redis/redis-server.pid
logfile /var/log/redis/redis-server.log

Among them, the slaveof parameter specifies the master node name and port number to which the slave node is connected; the port parameter specifies the listening port number of the slave node; the pidfile parameter Specify the save file of the process ID; the logfile parameter specifies the save path of the log file.

4. Application Scenarios

The master-slave replication function of Redis is widely used in the following scenarios:

1. High availability: The master-slave architecture allows slave nodes to take over from the master node. role, thereby achieving automatic fault transfer and rapid recovery;
2. Write load balancing: the master node is responsible for write operations, and the slave node is responsible for read operations, which can effectively share the load of the master node and improve the processing performance of write operations;
3. Data backup: The slave node can be used as a backup for the master node. When the master node data is lost or damaged, the data of the slave node can be restored;
4. Regional performance: Master-slave replication supports cross-regional data replication , which can realize applications such as off-site backup of data and low-latency reading.

5. Summary

Redis’ master-slave replication is a very useful distributed mechanism and plays an important role in Redis applications. This article provides a detailed introduction to the master-slave replication function of Redis, including definition, principle, configuration and application scenarios. I hope it can provide reference and help to readers.

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