SSDs have become fast, except in the cloud

Core count plus modern nvme actually make a great case for moving away from the cloud- before it was, "your data probably fits into memory". These are so fast that they're close enough to memory so it's "your data surely fits on disk". This reduces the complexity of a lot of workloads so you can just buy a beefy server and do pretty insane caching/calculation/serving with just a single box or two for redundancy.

I keep hearing that, but that's simply not true. SSDs are fast, but they're several orders of magnitude slower than RAM, which is orders of magnitude slower than CPU Cache.

Samsung 990 Pro 2TB has a latency of 40 μs

DDR4-2133 with a CAS 15 has a latency of 14 nano seconds.

DDR4 latency is 0.035% of one of the fastest SSDs, or to put it another way, DDR4 is 2,857x faster than an SSD.

L1 cache is typically accessible in 4 clock cycles, in 4.8 ghz cpu like the i7-10700, L1 cache latency is sub 1ns.

I wonder how many people have built failed businesses that never had enough customer data to exceed the DDR4 in the average developer laptop, and never had so many simultaneous queries it couldn't be handled by a single core running SQLite, but built the software architecture on a distributed cloud system just in case it eventually scaled to hundreds of terabytes and billions of simultaneous queries.