[pests]

A common problem would be throughput though. Storage capacity scales much faster than access speed. If you are storing an item only 3 times and lets say each storage location gives you 50,000 IOPS max then you can only ever service 150,000 IOPS of this item which might not be enough.

[dilyevsky]

Vast majority of data rarely (if ever) gets read so you use a cache for that