One big single redis instance for everything or multiple redis instances?

I have an expressJs server that manages many things including user sessions, message queues, caching data and socket.io all of this using redis. So my question is:

• Would it be better to use one redis instance for each purpose ( 1 redis for user sessions, 1 redis for message queues, 1 redis for data caching, 1 redis to manage socket.io sessions etc) ?
• Or is it better to use one single redis with prefixes ?

In both methods, what are the pros and cons ? (CPU, RAM consumption etc).

Thank you

It really depends on your setup, how much data you're storing, how often you do read/write, what the TTL for each cache and what the cost of all that look like.

However, generally I would suggest starting simply with one Redis instance until you see a need for having a more complex setup.