Redis Cookbook

Chapter 4. Redis Administration and Maintenance

In this chapter, we’ll try to focus on recipes related to operating Redis servers, instead of programming applications or data modeling. These tasks vary widely, but include starting a Redis slave, upgrading an existing server, performing backups, sharding, and handling a dataset larger than your available memory.

Configuring Persistence

Problem

One of the advantages of Redis over other key/value stores like memcached is its support for persistence—in fact, it even comes preconfigured with this support. This functionality enables you to perform some operations that wouldn’t be possible otherwise, like upgrading your server without down time or performing backups.

Nevertheless, persistence should be configured in a way that suits your dataset and usage patterns.

Solution

The default persistence model is snapshotting, which consists of saving the entire database to disk in the RDB format (basically a compressed database dump). This can be done periodically at set times, or every time a configurable number of keys changes.

The alternative is using an Append Only File (AOF). This might be a better option if you have a large dataset or your data doesn’t change very frequently.

Discussion

Snapshotting

As previously stated, snapshotting is the default persistence mode for Redis. It asynchronously performs a full dump of your database to disk, overwriting the previous dump only if successful. Therefore, the latest dump should always be in your dbfilename ...