[Taek]

A spinning disk iirc draws something like 15w. That's essentially true whether you've got a 1TB drive or an 8 TB drive. And it's only that high while the drive is spun up.

They are bulkier, but ultimately an SSD is going to need space and servers too.

It's not a competition at this point. SSDs are good if you need low latency or high IOPS, HDDs are good if small delays and low IOPS is acceptable, and tape is good if you don't mind waiting several minutes to get the data.

TCO drops significantly from SSD to HDD, and significantly again from HDD to tape. And a large, modern datacenter will frequently have massive amounts of all three.