Why storage tiers exist

Not all data is accessed the same way.

“hot / warm / cold” is relative, not absolute.

• Some data → accessed all the time
• Some → accessed occasionally
• Some → almost never, but must keep

Hot Storage

Data that is frequently accessed and needs low latency

• Very fast read/write
• Most expensive
• High availability
• Used by live systems

Cache (Memory-based)

• Redis
• Memcached
• In-process cache (Caffeine)