[Milhouse]

So the old cachemembuffersize 0 value, which buffers to the local disk has been deprecated?

That's a valid point... perhaps zero isn't an appropriate value with which to trigger this new behaviour.

My guess, though, is that 0 has been chosen as it's unlikely anyone with a Raspberry Pi would specify zero, given that caching to "local disk memory" (ie. SD, USB etc.) is going to be pretty slow.

Maybe I'm wrong though, and people are indeed caching to disk.