This will be achieved with QLC NAND flash memory, which features four bits per cell, resulting in 16 individual voltage stages for each cell. QLC-based SSDs could enable storage capacities of upwards of 100TB per disk, but the catch is that they're rated at only ~150 write cycles.
This is fine for archival storage requiring WORM workloads, and you still maintain NAND speeds when it comes to reading that data later on, meaning that decade old Facebook post will appear in your browser just as quickly as the one you posted ten minutes ago.
Facebook also shared some Intel Optane SSD benchmark results from RocksDB. Compared with the Intel P3600, the Optane prototype offered triple the throughput and a 10x latency reduction.
Via: PC Perspective