Hey. Just as a small starter. Storage groups only help you with syncing the appstacks between multiple datastores without you manually having to worry about it so that's where the storage group is for.
which type of automation is better?
Depends. If you set it to automatic you don't have any saying in when it happens. say for example you create 10 appstacks within an hour at some point all those 10 appstacks need to be syned from 1 datastore to another. If this happens when you also have a boot storm you might end up with LAN or IOPS issues. Normally I would always say let it run automatically, then you don;t need to worry about the sync.
Which type of strategy is better?
I'd say spread but I don't think it matters that much. Maybe someone else has a different opinion on the matter
Is it a kind of redundancy or helps us in performance?
Both. Depends on the size of your environment. Normally you can have up to 2000 connections to 1 appstack before you see performance degredation. If you have a smaller environment I would always suggest to have 2 datastores at least. If you have more than 2000 users I'd say always keep N+1 so with 2500 I'd say 3 datastores. But if users expierence slowness just add datastores if you can that IOPS level it to high.
