[vidarh]

It's not that simple. How much do you pay to keep those HDDs powered per TB per year? How much does maintenance cost (replacing drives etc.)? How does the low IOPS of those drives affect your workload?

SSDs may not win in every area yet, but if you only look at purchase price, you're not getting the right picture.

[tw04]

> How much does maintenance cost (replacing drives etc.)?

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.

[lostlogin]

Thanks. To add another layer to this, presumably SSD read/write is faster so there would be less time at max usage?

[tw04]

On paper, yes. But it really depends on the workload. At the end of the day, if you're architecting appropriately it's apple's and oranges. SATA/NL-SAS drives excel at large streaming workloads - think video rendering, storing large ISOs, video surveillance, database dumps.

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.

[ksec]

Yes but when you are looking at Petabyte scale system, unless those data are Hot and IOPs are concerned, HDD still wins given it is 10x cheaper.

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.

[LeifCarrotson]

It is not 10x cheaper, it is only cheaper to purchase initially.

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.

[sandworm101]

I think you overestimate the cost of electricity over the expected life of a drive. These arent space heaters. Pennies per day, adding up to perhaps tens of dollars difference between the two options.

[ksec]

I see, may be you should tell Blackblaze to switch over to SSD for their business model?

[LeifCarrotson]

Backblaze is in the backup industry, where fetch times don't really matter. When you have customers sensitive to app response time buying stuff, or engineers limited by how many times they can go through the edit-test cycle in 8 hours and "test" relies on how fast your media responds, then it matters.

[JumpCrisscross]

> the 10x gap between HDD and SSD

It's a 4 to 6x gap [1].

[1] http://www.pcmag.com/article2/0,2817,2404258,00.asp

[ksec]

1TB 2.5" HDD? You need to compare the sweet spot for SSD and HDD ( 3.5" ). And HDD easily outpace SSD, and 10x is only a generalization, in fact given the price of SSD is rising and HDD is slowing dropping, the sweet spot between the two is actually edging close to 20x soon.

[tracker1]

Funny, the 8TB drives I was looking at for a new NAS in a few months are around $300... I'm still debating between a 4 or 5-drive nas... but lets say, including the cost of the nas device I'm paying around $2k for 24TB of reduntant storage solution. 24TB of ssd storage alone will cost me over $6k, let alone the cost of a more expensive base NAS box, meaning 7-8K. That's upwards of 4X the cost.

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.

[brokenmachine]

I wouldn't use those 8Tb shingle drives for a NAS. In fact, that use is specifically mentioned as being not under warranty if I remember correctly.

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.

[tracker1]

The WD Red drives are expressly for NAS usage. Also, I'm aware of the slow redistribution of data. Generally there's only 0-2 connections on the NAS I have now, I just want more room. It's mostly BD/DVD rips, so if it dies, I can recover, it just takes a while. Reduced performance for a few days or a week isn't a huge deal for me.

[brokenmachine]

> The WD Red drives are expressly for NAS usage.

Oh, I was thinking about the cheaper Seagate "Archive" drives which have really slow write speed because of that shingled technology.

> Reduced performance for a few days or a week isn't a huge deal for me.

It could be a huge deal when another drive fails during that week while the array is rebuilding. But if you have more hot spares it's no big deal.

[runeks]

So if we're at only 3x the cost for SSD, how many years until HDD cost parity is reached? 5 years? This seems like a sensible guess to me.

[tracker1]

Process shrinks are increasingly expensive, so cost wise, I wouldn't expect it for another 10+ years.. also, if you need storage today?

[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.

[gareim]

We're talking about a ~10x difference right now. Do your factors sizeably reduce that gap? By how much do you estimate?

[agumonkey]

Are SSD better per Watt ? I used to see no difference for laptops models in the past years. I didn't check recently though (non sata devices etc).

[brianwawok]

No spinning parts. They do use less energy but not enough to make them more expensive TCO to SSD.