Using Redis as a cache storage for for multiple application on the same server
Generally, you should prefer the 1st approach, i.e. dedicated Redis servers. Shared databases are managed by the same Redis process and can therefore block each other. Additionally, shared databases share the same configuration (although in your case this may not be an issue since all databases are intended for caching). Lastly, shared databases are not supported by Redis Cluster.
For more information refer to this blog post: https://redislabs.com/blog/benchmark-shared-vs-dedicated-redis-instances
We solved this problem by namespacing the keys. Intially we tried using databases where each database ID would be used a specific applications. However, that idea was not scalable since there is a limited number of databases, plus in Premium offerings (like Azure Cache for Redis Premium instances with Sharding enabled), the concept of database is not used.
The solution we used is attaching a unique prefix for all keys. Each application would be annotated with a unique moniker which would be prefixed infront of each key.
To reduce churn, we have built a framework (URP). If you are using StackExchange.Redis then yuo will be able to use the URP SDK directly. If it helps, I have added some of the references.
- Source Code and Documentation - https://github.com/microsoft/UnifiedRedisPlatform.Core/wiki/Management-Console
- Blog Post (idea) - https://www.devcompost.com/post/__urp