“In retrospect, disk latency should have been an obvious concern early on in our database deployments.”
Google Cloud persistent disks take 1 to 2 milliseconds per read. Local SSDs take half a millisecond but come in fixed 375GB chunks and vanish when the host dies. Discord glued the two together with RAID to get both. The cloud sells you disks that are either slow or disposable, and you do the engineering to fix it.