SSDs may not win in every area yet, but if you only look at purchase price, you're not getting the right picture.
The maintenance on enterprise storage is generally a percentage of purchase price. So it's actually cheaper.
>How much do you pay to keep those HDDs powered per TB per year?
4.5 watts idle/8 watts max for a spinning drive vs. 4.5 watts idle/11 watts max for a large capacity SSD (15TB Samsung). The power consumption thing was a much better story comparing 3.5" 15k RPM drives. 7200 RPM drives it's basically a wash unless you're talking about relatively small capacity SSDs.
>How does the low IOPS of those drives affect your workload?
That's really the crux of the issue. SPINNING drives are not dead. FAST spinning drives are dead. 10k/15k drives are going to see the end of their useful life in the modern datacenter far faster than anyone predicted 2 years ago. Outside of legacy systems I would expect sales of 10k RPM drives to fall off a cliff if not completely disappear before the end of 2020.
SSDs are highly transactional workloads like databases or most back-end systems for applications or virtual machines.
You RARELY see the two used for the same type of workload unless someone has money to burn and wants to standardize on SSD and doesn't care about cost. SATA/NL-SAS being used for a workload that should be on SSD generally results in someone getting fired and the original system being forklift replaced.
And NAND has already hit the curve where it isn't going to get cheaper every year. NAND price is actually on the rise. Smaller Node is now actually more expensive, multiple layer are hard to yield.
So relatively speaking the 10x gap between HDD and SSD wont change in the next 5 years or so.
It is cheaper to power (NAND is more energy efficient than an electric motor), it is cheaper to maintain (solid state media does not suffer mechanical failures), and it is cheaper to use (each query on an SSD takes slightly less time than on spinning media).
It's only 10x cheaper if you ignore those facts. Now, how you value those factors may vary. Also, I have been involved in enough purchasing decisions to know that while capex is easy to approve and opex is hard, the initial number is surprisingly important.
It's a 4 to 6x gap [1].
That's the difference between something I can cover from my tax return, to something I won't really even consider. I won't save $6k in power in a year, or 5 to make up the difference, and I don't need the extra speed, to feed media to my htpc.
Also, if (when) a drive fails and you have to resilver 8Tb of data on one of those drives, the slow write speed will kill you.
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.
