Caching used to be terrible! We had 32 bit OSs 
Flash used to be for factories. Industrial machinery use cases.
“One day I put an SSD in my laptop and it could run faster than the production database cluster”
Add flash you need less RAM we could run Farmeville. This was how Fastly started.
“I heard you like databases so I put a database in front of your database for your cache to cache” @dormando
Memcache extstore. Store the metadata in Ram and data in flash.
Authoritative data in memcache means deletes and misses don’t have to go back to database. Writes are just flushes, efficient compaction. Works great for lots of use cases.
Often you can serve 99% off ssd without noticing
Companies are using this to drastically cut their compute requirements.
Tiered storage support, colocate the compacted items. Long ttl ends up in same tier, reduces fragmentation.
Persistent memory is coming. Plan is to hash the keys to make maximum use of each tier.
Getting to the data. On Optane you can hit 1ms target on 99 percentile at 500k/s requests. With 3 devices at around 800k/s before start to hit kernel issues.
Very close to RAM in performance but much chesper. More details in the blog posts
