What is Redis?

Redis is a fast in-memory NoSQL database and cache. Besides open-source, written in C, and designed for speed, Redis means “Remote Dictionary Server”.

Its fundamental data types are strings, lists, hashes, sets, and sorted sets; therefore Redis is often referred to as a data structure server. Many other data structures and capabilities for geolocation and stream processing are also available.

Redis’ various data structures are similar to the native data structures which are easily shared between processes and services, it’s great for rapid development and speedy applications.

Redis saves data in memory by default, with periodic disk persistence as an option. There are two kinds of disk persistence in Redis; RDB(Redis Database) and AOF(Append Only File). At certain intervals, RDB creates point-in-time snapshots of your dataset. AOF logs every write action received by the server, reconstructing the original dataset.

To prevent Redis from being full, you may set up a TTL(Time to live) to eject data when the specified amount of time elapsed.

This article focuses on Standalone Redis, Redis Sentinel for high availability, and Redis Cluster for automatic partitioning, as well as their advantages and disadvantages.

What is a Single Redis Instance?

It’s a solution using the single Redis node deployment architecture.

more

https://medium.com/@chaewonkong/redis-sentinel-vs-redis-cluster-a-comparative-overview-8c2561d3168f

https://medium.com/hepsiburadatech/redis-solutions-standalone-vs-sentinel-vs-cluster-f46e703307a9