Do Hard Drives Still Make Sense for Your Data Center?

It’s been a raging debate in the data center sector for years now: hard disk drives vs. solid state drives. Regardless of hype, what’s the best deal for your data facility?

Both have advantages, and both have their proponents. Certainly the HDD has a stronger legacy position and a lower price point. Yet SSDs are clearly faster – flash drives are the high end sports cars of the hardware world.

To provide advice on the most effective strategy for today’s data center, I spoke with an industry expert, Colin Presly, Senior Director, Office of the CTO, Seagate Technology. 

Among the topics covered:

• Some analysts in the IT industry have predicted that the HDD will soon be replaced by the SSD, especially as flash prices have fallen. Is this what you see happening?
• How does the TCO of hard drives vs. TCO of SSDs at scale compare? And what light can TCO shed on this issue?
• What’s the ratio of hard drives to solid state drives in an average cloud data center?
• Can you address arguments in favor of SSDs that rely on TBW and data reduction?
• So the hard drive has a brighter future than some foresee. To what extent is the hard drive’s continued resilience a result of the evolution of the format, technologies like HAMR and dual actuator tech?
• What about the role of cloud service providers? What do hyperscalers mean for balance between SSD vs. HDD?
• How about the impressive performance levels of SSD? Surely, the data bears those out?
• What do you see as the macro trends in data storage in the years ahead?

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Edited highlights from discussion:

Today we’re talking about hardware – but it seems the tech world is obsessed with software.

“Absolutely. Seagate, we’re a hardware company fundamentally. However, we are moving more into software, and we understand that software is a big piece of the world. And software-defined is there because the world is changing so quickly, and for the world to change quickly, you really need software to be able to make that change.

What we see more of is such an open ecosystem now in software, and that’s actually moving into open in hardware as well. With massive developer communities that are developing software together as an industry, ’cause the industry problems are so big that we really need to solve them together, not individual companies.

So yeah, we absolutely acknowledge software is a big piece. What I think we see is that we need to necessarily maybe reduce the cost of the software, because the cost of the software can become prohibitive to the ecosystem growing. So anything we can do to help grow the open communities and reduce the cost of the software there, we can drive more value towards the hardware and ultimately the whole ecosystem can grow that way.”

Some analysts say, “We’re coming to a day where the hard disk drive is going to reach its sunset.” Everything’s going to be flash-dominant, especially as flash drive prices have fallen. How do you see that particular macro trend working out?

“No, that’s really not the way we see it at all now. Solid-state devices are really incredible devices, and there’s a lot of innovation going on in that space. And absolutely true that prices have fallen, and they’re in a different class relative to performance from a hard disk drive.

So all of those things are true, but if you really look at it, the cost differential is still very, very high. You’re talking at least eight to 10x from just a device cost perspective. And while it’s pretty easy to find use cases where it makes sense to move from an HDD to an SSD, maybe in consumer solutions or areas of enterprise performance where performance really dominates all other metrics. Absolutely, it makes sense.

But we like to look at it really that they’re not essentially competing technologies, they’re very complementary technologies.

We need SSDs to be successful as an industry to be able to grow hard drives, to be able to grow storage. We shipped one zettabyte of storage last year as an HDD industry. It’s a massive amount and we’re anticipating to ship four more zettabytes in the next five years. The amount of storage that needs to be created, it’s just immense, so we need SSDs and HDDs to be successful for that.”

The consumer world has made more of a switch to solid-state than the enterprise world, true?

“Oh yeah, that’s absolutely accurate. And I think that’s sometimes where some of this confusion comes in, is the devices we see every day and we work with in our laptops and our phones are transitioning that way.

But I think what the pieces people don’t see is that, what those things are actually doing is they’re enabling really more storage in the data center. Everybody’s taking photos on their phones. IoT now is just emerging. The IoT devices are going be talking to each other, transmitting data, and cars are going be transmitting data and talking to each other. All this data is just going explode. And this data that we don’t necessarily see and interact with as a user, that data has to go somewhere, and it ultimately ends up in the data center.”

Certainly, if you look at the hard disk drive as a format, it continues to evolve in terms of its capability. There’s things like the HAMR, there’s dual actuator technology. I’m assuming these are some of the technologies that are keeping the hard disk drive alive going forward.

“For us, we see massive room for innovation still within the HDD piece. Clearly, perpendicular recording, which is the recording technology we’re currently on. Perpendicular recording is somewhat coming to the end of its life. We see diminishing returns right now in terms of growing areal density with the perpendicular technology.

But yeah, HAMR, heat-assisted magnetic recording. That has a massive promise for increase in areal density. We just had a recent analyst event where we showed some of that data. We have lab demonstrations showing devices that could go to 50 terabytes by 2026, even 100 terabytes by 2030 potentially.

So that allows us to fundamentally really increase the cohesivity of the disk, and then using heat to essentially temporarily lower the cohesivity as we write it, we can achieve massive increase in areal density. So with heat-assisted…we’re already shipping that technology today, and we have plans to transfer to that over the next decade. It will provide us a really big boost.

So as we increase capacity with HAMR, we also do need to address areas where some customers become starved of their capacity because they don’t have enough performance. So even though we’re not still trying to compete with a solid-state drive in performance, what we’re trying to do is keep the access to the data to a point where it’s useful for customers.

And so by adding in a second actuator to the drive, we’re actually now able to double the amount of accessible capacity for customers that have become constrained. So we also have a solution to that to match with HAMR. So, yeah, lots of innovation in the hard drive business.”

Let’s look to the future. What about the trends in the data storage industry, and in the hardware data or software in the data storage industry in the years ahead. What do you see happening and how might a company get ready for that now?

“So one big trend we see is composability and disaggregation as a general trend. There was a phase where companies went to hyper-converged infrastructure for easier deployment, where you put storage, compute networking together.

Now we’re starting to see a trend away from that and more towards composable architectures where you tend to see optimal systems for storage, for compute, for networking acceleration. And these are all backed by new fabrics like NVMe over fabric. There’s new [trends] like memory disaggregation; by being able to disaggregate all the components of the ecosystem, you’re now able to scale independently, whereas before when you converge everything together, you become locked with certain ratios of storage, compute memory. And by disaggregating everything, now you’ve got to a point where you can scale them differently.

And that comes back a little bit to the software too, once you’ve now got to a hardware disaggregation that really enables new techniques like containers and Kubernetes. These types of technologies that can compose different services and storage and compute above the devices, allows much easier provisioning of those because now you can access those type of resources on demand and be able to scale them independently. So that’s a really big trend.

So other ones are security, it’s clearly a big one, massive, the whole industry, intense security with a fundamental tenant of security at rest. We’re seeing much more prominence in people wanting to secure their data at rest and in flight as well. So those two are big ones.

And then back to the software piece, object storage, we do see that that is growing and growing and growing. People need big, cheap ways of storing data and object storage is really, really good for that, and it has a very rich metadata associated with it.

So the ability to find the data and be able to use it and unlock it, feed it into different AIML algorithms, object storage is really, really growing and there’s a very vibrant open-source community too that we’re now contributing to with Seagate’s CORTX solution. It’s a way of really unlocking the value of object storage and making it cost-effective for the world.”