We have a production service running for years that just mmaps an entire SSD and casts the pointer to the desired C++ data structure. That SSD doesn't even have a file system on it, instead it directly stores one monstrous struct array filled with data. There's also no recovery, if the SSD breaks you need to recover all data from a backup. But it works and it's mind-boggingly fast and cheap.
I've always wanted a Smalltalk VM that did this. Eternally persistent VM, without having to "save". It just "lives". Go ahead, map a 10GB or 100GB file to the VM and go at it. Imagine your entire email history (everyone seems to have large email histories) in the "email array", all as ST objects. Just as an example. Is that "good"? I dunno. But, simply, there is no impedance mismatch. There's no persistence layer, yo…
Non-volatile memory right in the CPU memory map. No "drives", no "controllers", no file allocation tables or lookup lists or inodes. Save to memory 16GB and it's there even through reboots.