Solid State Hybrid Drives – The Natural Evolution of Storage

In the world of data storage technology, there are three fundamental necessities that drive invention: capacity, performance and price. Widespread adoption depends largely on a technology’s ability to deliver all three with the least amount of disruption to the user experience, not on the notion that any single technology can have a de facto impact on the hard drive market.

Over the last five years, few markets have faced more pressure from so-called disruptive technologies than the hard drive market. The advent of cloud computing, the mainstreaming of the smartphone, the resurrection of the tablet, the rise of flash as primary storage for mobile computing, and solid state drives for performance-challenged enterprises have seemingly heralded the beginning of the end of the hard disk drive. However, Seagate has consistenly maintained that the adoption of such technologies is, in fact, the very catalyst to the exploding demand for hard disk drives.[1]

For a technology to obtain widespread adoption, it must evolve, and technology evolves in steps – steps that over time eliminate complexity and deliver a significantly improved, yet very familiar experience. Consider the media tablet. The Microsoft Tablet PC concept launched in 2001 was the first of a potentially disruptive technology. But it was almost ten years later, when Apple released the iPad, that the tablet earned widespread adoption. Why? Because Apple provides a device that is fun to use and delivers an improved, yet familiar user experience. Like the media tablet, the hard disk drive has been a part of evolutionary steps over the past 30 years; it has led in developments as well.

One Small Step, One Giant Leap

In a span of three decades, the hard drive has enabled the invention of new technologies. The meteoric growth of the operating system and its software, the personal computer, the network, the Internet, the cloud, and yes, smartphones and media tablets would, arguably, not be possible if it weren’t for the hard drive. What’s more, as such technologies are developed further, their survival may not be possible without it.

With each improved user experience, there was a corresponding evolution of the hard disk drive. The laptop was driven by the evolution of 2.5-inch drives with lower power and higher durability; the DVR and gaming consoles by high-capacity, low-power, yet silent drives; the modern day data center and cloud computing by advancements in interface, capacity, performance, power and reliability.

Consumers and businesses are not going to discard proven technology all at once for an entirely new and unfamiliar experience. They seek the next great step that takes their existing experience and simply makes it better. Solid state hybrid drives (SSHDs) do just that.

The Natural Evolution of the Storage Experience

Seagate first introduced a hybrid drive in 2007 with the Momentus PSD product, which featured 128MB or 256MB flash options, was 100% reliant upon Microsoft Vista’s ReadyDrive and emphasized power efficiency for a better mobile experience. However, the product was not widely adopted, primarily because it didn’t deliver capacity, performance and price with the least amount of disruption.

Three years later Seagate introduced a new hybrid – the Momentus XT drive – and coined the term solid state hybrid drive. This time the focus was on delivering the necessities of capacity, performance and price with zero disruption to the user experience. The result? Seagate Adaptive Memory technology allows users to experience real world system performance gains of up to 50% without third-party software or operating system dependencies. It was a hit. Within a year, Seagate had shipped over one million Momentus XT solid state hybrid drives.

Unlike competitive technologies (such as SSD, PCIe, flash cache modules or software like Intel’s Smart Response Technology), which require differing levels of integration experience and expense for consumers and businesses alike, SSHDs look and act like traditional hard drives. There are no compatibility dynamics with operating systems, applications, or network and storage management programs. There are no physical obstacles associated with system architecture, design or expansion capability. And there are no economical constraints with transitioning existing hardware or software investments to best take advantage of such technology. Throughout the evolution of the hard disk drive, systems became more dependent on seamless integration achieved through the intelligence being designed into the disk drive. Such intelligence is critical to achieving success and providing minimal disruption to the user.

How SSHD Will Redefine the Hard Drive Market

Since the first commercial usage of hard disk drives that began in 1956 with the shipment of an IBM 305 RAMAC, the disk drive has rapidly evolved in five distinct ways: form factor, capacity, performance, interface and reliability. Over the past 5 years, we have seen the evolution slow.

•       Form factors have standardized on 2.5-inch and 3.5-inch. Drives may get thinner (7mm), but their footprint most likely will remain the same.

•       Capacity has been growing at a steady clip, but even that is threatened by the areal density limitations of perpendicular magnetic recording (PMR). It won’t pick up again until heat-assisted magnetic recording (HAMR) becomes feasible.

•       Performance gains, for quite some time, have been limited by both areal density improvements and the speed at which the disks can physically spin (RPMs). There is no sign of an increase beyond 15K RPMs.

•       Interfaces will continue to evolve, with 6Gb/s SAS and SATA 6Gb/s being the latest iterations. Plans exist to move to 12Gb/s SAS in the next year, but SATA is expected to stall at the 6Gb/s speeds available today

•       Reliability is a given. Hard drive manufacturers continue to push annual failure rates (AFR) down, and mean time between failures (MTBF) hours up, especially on enterprise-class drives, but guaranteeing reliability has its limits no matter the technology.

Such limitations put added pressure on hard drive manufacturers to evolve. Capacity improvements and interface speeds alone may meet the necessities of invention (capacity, performance, price) and provide the least amount of disruption to the user experience today, but the user experience is also evolving. Advancements in software, processors, memory and network bandwidth are driving demand for an even faster user experience. Because of this, hard drive manufacturers will see a shift in the evolution of disk-based storage from an overarching emphasis on capacity to a rapidly growing emphasis on performance.

IBM researchers show (Figures 1 and 2) that areal density improvements are expected to maintain a CAGR of 25% to 40% over the next few years (Figure 1), while the maximum sustained transfer rates of drives have begun to level off (Figure 2).[2] The demand for improved performance has never been so evident.

Flash memory is the answer to the demand for performance. By integrating a small amount of flash into the hard drive, creating an SSHD, users get many of the performance benefits of flash technology without the added cost. In addition, when packaged in a 2.5-inch or 3.5-inch form factor and coupled with built-in intelligence, SSHDs provide the necessities of capacity, performance and price with the least amount of disruption to the user experience.

When it comes to hard drives, there will always be capacity growth, evolving interfaces and steady improvements in reliability, but what will begin to take center stage is the storage supplier’s ability to differentiate on performance. SSHD technology with intelligence designed in is the natural path to enabling such differentiation, thus redefining the hard drive market in the next three years. Today, 2.5-inch solid state hybrid drives (SSHDs) for laptops already exist, and with 2.5-inch enterprise SSHDs and 3.5-inch desktop SSHDs coming in 2012, this natural evolution of storage is already upon us.

As Bill Buxton, a pioneer in computer graphics who is now a principal researcher at Microsoft says, “Anything that’s going to have an impact over the next decade—that’s going to be a billion-dollar industry-has always already been around for 10 years.”[3]

[1] Seagate, Cloud Computing—Answering the Need for Storage Best Practices, PV0018, and Media Tablets – The End of HDDs?, PV0005

[2] IBM, GPFS Scans 10 Billion Files in 43 Minutes, 2011

[3] Wired, Clive Thompson on The Breakthrough Myth, August 2011

Rajesh Khurana, country manager – India & SAARC, Seagate technology
[email protected]