Log-structured file systems: There's one in every SSD

When talking to hardware people who want to market PCM, you may notice that it suffers a similar problem as flash SSDs do. Since there is no PCM software stack, they want to plug into an existing software stack by pretending to be something else. And from what I've heard so far, that something else will be NOR flash.

Which isn't too bad an idea, honestly. 100M may seem big, but if you are ignorant enough and write your filesystem superblock on every sync, you can have that worn out in just 24h. So you still need some amount of wear leveling.

Plus, the programming of PCM is asynchronous. Flipping a bit one direction is about 6x slower than flipping it the other way. Which means that by treating your random-writeable PCM as block-eraseable flash you gain a speedup that can more than counter the slowdowns from garbage collection under fairly realistic conditions.