What is the method of achieving persistence in Redis?

There are two methods in Redis for achieving persistence: RDB (Redis Database) and AOF (Append Only File).

1. RDB persistence: RDB is the default persistence method for Redis. It saves data from memory to disk through snapshots. When automatic saving rules are configured (such as every certain period of time, after a specified number of key-value pairs have been modified, etc.), Redis will generate a compressed binary file of the data in memory and save it to disk. RDB persistence is suitable for scenarios like backup, disaster recovery, and large-scale data restarts.
2. AOF persistence: AOF records all write operations in Redis in the form of a log. Each write command to Redis can be appended to the AOF file, allowing data recovery through replaying the commands in the AOF file when Redis is restarted. AOF persistence is suitable for scenarios where data security is of utmost importance. Although AOF files are typically larger than RDB files, the AOF method offers higher data security and reliability.

One can choose the appropriate persistence method based on specific business needs and requirements for performance and data security, and can also use both RDB and AOF methods concurrently for data backup and recovery purposes.