[jeffbee]

In terms of volumetric density, flash is already much higher. A 4TB m.2 2280 SSD is ~70 times smaller than a 16TB 3.5" HDD.

[magicalhippo]

Yes, I was imprecise, I meant at roughly the same cost.

Just seems that the spinning rust guys have to jump through some pretty extreme hoops to get density up, while the flash guys "just" have to reduce cost, which gives them more angles of attack (ie either further density increase or process optimization).