> RAM is for volatile data, disk is for data persistence.

Genuinely curious where this idea has come from. Is it something being taught currently?

No, not currently -- since the start of computers. This is quite literally part of Computing 101; see https://web.stanford.edu/class/cs101/lecture02.html#/9 , slides 10-12.

You can ask your favourite search engine or language fabricator about the differences between RAM and disk storage, they will all tell you the same thing. Frankly, it's kind of astonishing that this needs to be explained on a site like HN.

	▲	112233 10 hours ago \| parent [-]
		I have no idea where on those slides it says non-volatile storage should not be used for non-permanent, temporary data. It does note main differences (speed, latency, permanence). How does that limit what data disk can be used for? What would one use optane DIMMs for? Also, if my program requires huge working set to process the data, why would I spend the effort and implement my own paging to templrary working files, instead of allocating ridiculous amount of memory and letting OS manage it for me? What is the benefit?