Redis cluster expansion plan and implementation details

Redis is a high-performance open source memory data storage service. It is increasingly favored by developers because of its fast read and write speed, persistent storage and support for multiple data structures. As the business continues to grow, the storage capacity of Redis can no longer meet the demand, and it needs to be expanded. This article will introduce the Redis cluster expansion plan and its implementation details.

1. The concept of Redis cluster

Redis cluster refers to connecting multiple Redis instances together to form a large set of Redis instances, which can improve the availability and capacity of Redis . In a Redis cluster, each instance is responsible for saving part of the data, and all instances work together to form a logical Redis instance. When there is new data that needs to be stored, hash calculation is performed based on the Key value of the data, and the corresponding instance is selected for storage.

2. Expansion plan of Redis cluster

The expansion of Redis cluster is divided into two methods: vertical expansion and horizontal expansion.

2.1 Vertical expansion

Vertical expansion refers to improving the capacity and performance of the Redis cluster by increasing the hardware performance of the server, including the upgrade of CPU, memory, hard disk and other hardware. The advantage of vertical expansion is that it is simple to operate, does not require data migration, and has a small impact on the business. However, the disadvantage is that it is more expensive, cannot meet high concurrent read and write requirements, and is difficult to ensure high system availability.

2.2 Horizontal expansion

Horizontal expansion refers to expanding the capacity and performance of the Redis cluster by increasing the number of server nodes, including splitting, merging, horizontal expansion and other methods. The advantage of horizontal expansion is that the cost is relatively low and it can meet high concurrent reading and writing requirements. The disadvantage is that data migration is required, which has a greater impact on the business.

3. Redis cluster expansion implementation

Generally, we expand the Redis cluster by adding Redis nodes. The specific implementation steps are as follows:

3.1 Create a new Redis node

First, we need to install the Redis service on the new server, and then modify the configuration file. The configuration file needs to specify the port of the node, the IP address of the node, the node type as slave, and the IP address and port of the master node.

3.2 Add the new node to the cluster

Run the command redis-trib.rb to bind the original node and the new node:

redis-trib.rb add-node new_node_ip:new_node_port old_node_ip:old_node_port

3.3 Data migration after adding nodes

At this time, the new node has joined the Redis cluster, but there is no data yet. We need to transfer data through data migration, migrating part of the data from the original node to the new node. Redis provides migration instructions as follows:

redis-cli --cluster reshard old_node_ip:old_node_port

After the instruction is executed, you will be prompted to enter the amount of data to be migrated and the IP of the target Redis node. Address and port number, etc. During the migration process, the original Redis node needs to use part of the bandwidth to send data to the new Redis node, which may have a certain impact on the business. Therefore, data migration should be carried out during low business peak periods to avoid affecting service quality.

4. Redis cluster maintenance after expansion

After the Redis cluster is expanded, the Redis cluster needs to be maintained to ensure the high availability of the system. The main maintenance methods include:

4.1 Monitor the running status of the Redis cluster

It is necessary to monitor the running status of the Redis cluster in real time and understand the read and write QPS, memory usage, request response delay, and network of the cluster. Bandwidth occupancy and other indicators, problems can be discovered and dealt with in a timely manner.

4.2 Unified management of Redis cluster

Conduct unified management of Redis cluster, including cluster backup, recovery, fault handling, upgrade and other important tasks. In addition, cluster data also needs to be backed up and restored to ensure data availability and security.

5. Summary

Redis cluster is a high-availability, high-performance, and scalable data storage solution that can meet the needs of different businesses. During the Redis cluster expansion process, we need to choose an appropriate expansion plan, migrate data during low business peak periods, and conduct unified management and maintenance of the expanded Redis cluster to ensure system stability and high availability.

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