The leader-follower architecture in Redis High Availability is a common architectural pattern for data replication and failover. In this architecture, one node acts as a leader and is responsible for receiving and processing writes, while the other nodes act as followers and are responsible for copying data from the leader node. This architecture ensures data consistency and reliability.
The leader-follower architecture is a master-slave replication method that improves the availability and reliability of the system by replicating data to multiple nodes. In Redis, the leader node is responsible for receiving write operations from the client and copying these operations to the follower node. The follower node replicates the data of the leader node to achieve data consistency with the leader node.
Data consistency is an important consideration in a leader-follower architecture. Here are some measures to ensure data consistency between leader and follower:
Write replication: When the leader node receives a write operation, it records the operation in the log and sends the corresponding write operation to all follower nodes. The follower node performs these operations one by one in the order of the received write operations to ensure data consistency.
Data synchronization: To ensure data consistency, follower nodes need to periodically synchronize data from the leader node. This can be achieved through the replication feature of Redis. The follower node will connect to the leader node and send a sync command, and the leader node will send a snapshot of its own data to the follower node for initialization. After that, the leader node will send its own writes to the follower node to keep the data in sync.
Read Operation: When a client sends a read operation, the server usually sends the request to the follower node. This relieves the load on the leader node and increases the read throughput of the system. Although the read operation is performed on the follower node, the client can get the correct result because the data between the leader and follower is consistent.
Asynchronous replication: Data replication between the leader node and the follower node is usually done asynchronously. This means that the leader node does not wait for the follower node to confirm and proceed with other operations. While this can improve the performance and responsiveness of the system, it can also cause a slight lag in the data. In some cases, if the leader node goes down, there may be a small part of the data loss.
Data integrity check: To ensure the integrity of the data during the replication process, the leader node usually uses checksums or hash functions to sign the data. The follower node will use the same checksum or hash function to verify the data after receiving it. If the signatures of the data do not match, the data may be tampered with or lost, and the follower node will re-request the data.
In Redis high availability, the leader-follower architecture is a common architectural pattern for data replication and failover. You can ensure the consistency and reliability of data between the leader and follower through measures such as write replication, data synchronization, read operation, asynchronous replication, and data integrity verification.