Comment by twotwotwo

They mention it as a block device, and the diagram makes it look like there's one reader. If so, this seems like it has the same function as the page cache in RAM, just saving reads, and looks a lot like https://discord.com/blog/how-discord-supercharges-network-di... (which mentions dm-cache too).

If so, safe enough, though if they're going to do that, why stop at 512MB? The big win of Flash would be that you could go much bigger.