Helium Taking HDDs to New Heights

Transcription

1 White Paper Helium Taking HDDs to New Heights Sponsored by: HGST, a Western Digital company David Reinsel November 2013 John Rydning EXECUTIVE SUMMARY Current hard disk drive (HDD) technology is reaching the upper plateau of a technology "S" curve, constraining in the near term the ability of manufacturers to increase the storage capacity of a disk drive. Recently, the maximum capacity of HDDs has been doubling every two to three years. In contrast, a decade ago, the maximum capacity of an HDD was doubling every year. The slowdown in HDD storage capacity increases is intersecting with datacenter capacity requirements, growing on average at a rate of more than 40% per year. For some hyperscale datacenters, storage capacity requirements are more than doubling each year. A fundamental change in the trajectory of HDD capacity improvements is necessary, or else IT managers will be compelled to undertake massive datacenter projects that include provisioning for growing power and cooling requirements just to accommodate a rapidly rising number of HDDs deployed in a datacenter. HGST has developed an innovative new HDD technology called HelioSeal, a sealed helium-filled HDD platform, to help IT managers address the challenging total cost equation associated with datacenter storage capacity growth. The sealed helium-filled HDD platform is evolutionary in that it can be easily integrated into existing server and storage system architectures. However, it is revolutionary from the standpoint that it enables the development of higher-capacity HDDs more quickly than the current HDD technology allows and becomes a new building block for the HDD industry for the next 10 years. In a nutshell, the helium-filled HDD platform will make it possible to kick-start the development of new, innovative storage solutions for specific customer needs and use cases, including cold storage applications. IT managers utilizing high-capacity sealed helium-filled HDDs in servers and storage arrays will simultaneously realize a reduction in datacenter power consumption and cooling costs while pushing storage density to new heights. November 2013, IDC #244199

2 (%) INTRODUCTION HDD industry petabyte (PB) shipments for enterprise applications have been growing at a 45% compound annual growth rate for This means the storage capacity of the average datacenter is doubling about every two years. HDD PB shipment annual growth rates vary each year, depending on macroeconomic conditions and the timing of large hyperscale datacenter installments (see Figure 1). Despite year-to-year variation for HDD PB shipment growth rates for enterprise markets, the secular trend is clear: Content growth is driving datacenters to acquire thousands of HDDs each year to expand storage capacity quickly. By 2020, roughly 67% of all petabytes of data will be stored on HDDs. FIGURE 1 Worldwide HDD PB Shipment Annual Growth Rates for Enterprise Applications, Source: IDC, 2013 IT hardware budgets are straining to support the growing volume of digital content organizations desire (or are required) to save. At the same time, IT managers also face a daunting challenge to reduce power consumption for running servers and storage systems, including the power required to cool a datacenter. Adding to IT hardware budget pressures are slowing price reductions for HDD storage on a dollar-per-gigabyte basis. At one time, organizations could expect to realize HDD price declines on a dollar-per-gigabyte basis of -30% to nearly -40% per year (see Figure 2). However, a combination of HDD market and technology dynamics is slowing HDD dollar-per-gigabyte price declines to a compound annual growth rate of -20% IDC #

3 (%) FIGURE 2 Worldwide Enterprise HDD Annual Dollar-per-Gigabyte Change, Source: IDC, 2013 Today's enterprise datacenter economics are challenged. Over the next several years, IT managers will need storage solutions that cost less per gigabyte than current HDD technology solutions are delivering to keep up with storage capacity growth requirements economically. One of the factors causing sluggish HDD dollar-per-gigabyte price declines is slowing HDD areal density growth. HDD areal density is a measure of the amount of information or data that can be stored per square inch or square millimeter on a disk surface. HDD areal density improvements are highly correlated to HDD dollar-per-gigabyte reductions. IDC tracks the areal density of all HDDs that have been shipped for enterprise applications. An analysis of the average areal density shipped in HDDs for enterprise applications reveals that HDD areal density has been slowing since 2008 (see Figure 3) IDC #

4 (%) FIGURE 3 Enterprise HDD Areal Density Annual Growth Rates, Source: IDC, 2013 Without the aid of areal density growth, the only way to increase the capacity of an HDD is to add heads and disks to the drive. However, HDD mechanical design constraints effectively limit the number of heads and disks that can be added to a given HDD. HDD Technology Drives Down the Cost of Storage Successive HDD technology "S" curves have led up to today's capacious HDDs, with each new technology "S" curve building upon prior HDD technologies deployed. The most recent HDD technology making possible 1TB of storage capacity per disk is perpendicular magnetic recording (PMR), which still leverages the prior technology, giant magnetoresistive recording (GMR). Each major HDD technology "S" curve eventually reaches a plateau in terms of the achievable maximum areal density. As any given technology approaches its plateau, HDD researchers are developing the next technology to further increase HDD storage capacity per disk. The next two HDD technology "S" curves currently in development to extend PMR technology are shingled magnetic recording (SMR) and heat-assisted magnetic recording (HAMR). Historically, the HDD industry has successfully prepared the next HDD technology for volume production just at the point when the prior technology is reaching its areal density limit. Unfortunately, this time is different. SMR technology is beginning to ship in volume now, and SMR will help increase the storage capacity per disk somewhat over the next few years, but the capacity increases realized from SMR technology will be relatively minor. The next major HDD technology introduction that will boost HDD areal density significantly is HAMR, which still requires three to five years of development before it is ready for volume production IDC #

5 HDD areal density (Gb/in. 2 ) Figure 4 shows the increase in HDD areal density made possible by GMR and PMR technology "S" curves since 1995 and the expected increase in HDD areal density made possible by SMR and HAMR through FIGURE 4 Leading-Edge HDD Areal Density and HDD Technology "S" Curves, ,000 1,800 1,600 1,400 1,200 1, HAMR SMR PMR GMR Best commercialized HDD AD Source: IDC, 2013 Increasing the Capacity of an HDD by Adding Heads and Disks to the Drive The HDD industry will operate at the plateau of the PMR technology "S" curve from 2014 to 2017 (refer back to Figure 4). SMR technology will allow for some growth in the storage capacity per disk but not at a pace sufficient to keep up with datacenter storage capacity growth. In short, HDD areal density growth will be relatively slow for the next three to five years. Although areal density growth will be slow, HDD manufacturers can still meet customers' growing capacity demands with higher-capacity HDDs by taking another path: adding heads and disks to the drive. Today's highest-capacity, multi-terabyte HDDs have up to 5 disks and 10 heads per drive. The physical dimensions of these high-capacity drives allow for up to 2 more disks and 4 more heads to be added to the drive, bringing the total to 7 disks and 14 heads per drive, a 40% increase in storage 2013 IDC #

6 capacity. But HDD mechanical limitations present challenges for adding heads and disks to a drive while still ensuring the drive will operate reliably in the field especially in densely packed storage arrays. Helium Rises to the Occasion to Lower Storage Total Cost of Ownership When the HDD is in operation, the disks spinning inside the cavity of the drive create wind turbulence that makes it difficult to keep the heads on track over the disk surface. Generally, as more disks and heads are added to the drive, the wind turbulence inside the drive increases. Adding disks to the drive also adds weight or mass, which means more power is required for the spindle motor to spin the disks. But adding a disk also increases the surface area inside the cavity of the drive that is generating air friction while the disks are spinning, again increasing the power required to spin the disks. Filling the cavity of an HDD with helium nearly eliminates the wind turbulence that disturbs the heads. This gives HDD manufacturers design freedom to add more disks and heads to an HDD to reach a higher capacity without adversely affecting the drive's reliability. A sealed helium-filled drive cavity also significantly reduces the friction that occurs while disks are spinning inside the drive. Less power will be needed to operate a sealed helium-filled drive, and in the future, more disks could be added to the drive without adversely impacting power consumption. HGST's HelioSeal platform may be considered by some as unconventional. However, some HDD manufacturers already fill the drive cavity with helium temporarily during the HDD manufacturing process. Filling the drive cavity with helium temporarily is unexceptional. On the other hand, preventing helium from escaping from a disk drive over a prolonged period of time, over its entire useful life, is extraordinary. HGST's sealed helium-filled platform has achieved this feat through a combination of its proprietary product design and manufacturing process. A sealed helium-filled platform simultaneously contributes important total cost of ownership (TCO) benefits to future HDD products, including: Ability to add heads and disks to reach higher HDD capacity points Lower dollar per gigabyte More storage capacity and less weight per area in the datacenter Lower power consumption Lower cooling costs Mitigates the risk of humidity changes or contamination affecting drive reliability, which opens up new operating environments previously off-limits to HDDs Figure 5 depicts some TCO improvements made possible with a sealed helium-filled drive as compared with a conventional air-filled disk drive IDC #

7 FIGURE 5 HDD TCO Improvements Helium Platform TCO Improvements 6TB 7-disk Helium HDD vs 4TB 5-disk Air HDD 50% 23% 49% 50g 38% 4 o C More Capacity Lower Idle Power per Drive Lower Watts per TB Lighter Lower weight per TB Cooler Source: HGST, a Western Digital company Lowering the cost to acquire and manage storage capacity is a top priority for datacenter managers, especially when confronted with managing rapid content growth. HDDs with higher disk counts, thus higher capacities, help bring down storage TCO. According to HGST, 20 30% TCO savings have been cited by HGST customers testing sealed helium-filled HDDs. The bottom line: A sealed helium-filled drive platform can change the discussion from delivering capacity only (a technology gain) to delivering capacity plus TCO (a business value). Sealed helium-filled HDDs also give datacenter managers an option to extend legacy platforms and maximize ROI by retrofitting existing arrays with higher-capacity sealed helium-filled HDDs IDC #

8 Future Use Cases for HGST's Sealed Helium-Filled HDD Platform Cold Storage It's Not "What" But "Where" to Store Data Applications have a variety of data access frequency and data retrieval latency requirements. Various use cases for storing data overall have a range of access latency expectations and requirements. At the same time, new use cases for storing copies of data are emerging. Cold storage technology is embryonic but is emerging as a solution to a wide range of storage challenges. Cold storage technology requires an integrated and complete solution encompassing the storage devices, the storage system architecture or configuration, and the storage software. Tape storage is currently the leading cold storage technology option, but only in certain situations that can tolerate very long latencies or in a given set of circumstances. Disk-based solutions are also being deployed for instances where long latencies associated with tape cannot be tolerated. The two use cases for cold storage in the datacenter are: Online cool: Low-latency applications such as long-tailed content associated with social media and that require access in the range of 100 milliseconds to 2 seconds Offline cold: For Web-based archiving, disk-to-disk backup, and long-term data retention applications, where lower cost per gigabyte and lowest power usage are critical considerations Key to any cold storage solution will be high-capacity mass storage devices that are readily accessible and can be "awakened" from an extremely low power (or no power) state. A sealed helium-filled HDD could provide many of the elements necessary to realize a mass storage device for future cold storage solutions. New "Out of the Box" HDD Designs and Configurations A sealed helium-filled platform also opens the door to new HDD designs and configurations previously considered unattainable at current (or future) areal densities. For example, sealed helium-filled HDDs with larger diameter disks or more disks can now be considered as options to yield more storage capacity per drive. CHALLENGES/OPPORTUNITIES HGST's HelioSeal technology is fully developed and ready for IT managers to use in today's servers and storage systems. Still, HGST will need to overcome a couple of challenges and harvest new opportunities to realize broad market adoption: Enterprise datacenter managers are often reticent to adopt new, relatively unproven technologies. Uptime in a datacenter as well as ensuring the data will not be lost is paramount. It will be necessary for HGST to educate customers and the marketplace in general on the maturity and reliability of HGST's sealed helium-filled HDD platform, especially relative to current and expected future capacity-optimized HDDs not using sealed helium-filled technology IDC #

9 Technology buyers often prefer more than one source to mitigate the risk of supply interruptions. HGST will need to assuage customer anxiety associated with sole-sourcing sealed helium-filled HDD products from HGST. Users need to be cognizant that a sealed helium-filled storage device opens the door to using HDDs in totally new operating environments. For example, sealed helium-filled HDDs can be immersed and operated in a non-conductive liquid, in a vacuum (outer space), or even in open-air datacenters. CONCLUSION HGST's HelioSeal HDD technology is intersecting the HDD market at the right time as enterprise datacenter customers require a clear path to sustained storage TCO reductions. HGST has been developing sealed helium-filled HDD technology since 2003 and today is the only HDD vendor that has readied this innovative, patented technology for introduction into a variety of enterprise HDD products. HGST has reported strong early adoption for helium-filled HDD technology among leading OEM and hyperscale datacenter customers including Code42, GreenRevolution Cooling, HP, Netflix, and Huawei Unified Storage. Over the next 10 years, the HelioSeal platform will also ease the way for the integration of future HDD technologies such as SMR, HAMR, or bit-patterned media (BPM) to deliver even higher-capacity disk drive products designed to address an array of diverse enterprise storage applications and use cases, including cold storage solutions IDC #

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