"An obvious question is why are we talking about spinning disks at all, rather than SSDs, which have higher IOPS and are the “future” of storage."
"The root reason is that the cost per GB remains too high, and more importantly that the growth rates in capacity/$ between disks and SSDs are relatively close (at least for SSDs that have sufficient numbers of program-erase cycles to use in data centers), so that cost will not change enough in the coming decade."
Well at least for YouTube video storage, I imagine the P/E cycles are not a problem. There have been issues with longevity like on the Samsung 840 EVO drives, but if you can avoid that then you can build some incredibly dense, fast, reliable and power efficient storage on top of V-NAND.
Cost per GB for SSDs is definitely catching up to HDD [1] and I think is expected to match or beat HDD within the decade. Power efficiency should be better on SSD and MTBF will be much better than HDD, so I would have thought TCO for SSD would have HDDs basically beat already.
"An obvious question is why are we talking about spinning disks at all, rather than SSDs, which have higher IOPS and are the “future” of storage."
"The root reason is that the cost per GB remains too high, and more importantly that the growth rates in capacity/$ between disks and SSDs are relatively close (at least for SSDs that have sufficient numbers of program-erase cycles to use in data centers), so that cost will not change enough in the coming decade."