Redis size assessment

Created by: orgalaf

Hi, Not really a bug rather a request for better docs. Recently tried deploying bull in production over aws elasticache to replace rabbitmq. We estimated the data size to be about 20GB and provisioned a 30GB redis instance. After about 15 mins in production we had about 10GB of data in redis and started getting OOM errors. A bit of research revealed that write heavy applications over redis (as bulljs is) can incur significant memory overhead up to twice the size of the actual data.

Would be good to get some guidelines in the docs about what size of instance to provision for the expected load.

Thanks