Capacity-Optimized Nearline SAS Drives Challenge SATA

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Data continues to be the lifeblood of many organizations. The unprecedented increasing demand to store that data is irrefutable. In a recent study, IDC predicted that hard disk drive (HDD) shipments for enterprise applications will increase from 40.5 million units in 2009 to 52.6 million units in 2014. In the same study, IDC also predicted the HDD industry “will ship more Petabytes for enterprise applications in the next two years than it did in the preceding 20 years.”

The demand for storing data spans across different applications and environments as well – each with their own unique data requirements. This data includes business-critical data that must be quickly accessible; highly sensitive data that must be secured; and secondary data that must be retained, but is infrequently accessed and for which cost containment is key. As such, the storage industry has responded with multiple drive types and tray-level drive intermixing to cost effectively meet application, rack, and energy efficiency requirements within a single storage system.


The demand for capacity-optimized drives, where capacity and cost rule over performance, has contributed much of the growth in overall drive sales. Between 2009 and the first half of 2010, capacity-optimized drives experienced 30.5 percent year-over-year growth (IDC Worldwide HDD Shipments and 4 Quarter Outlook by Segment – Final C2Q Results). IDC also forecasts that by 2011, more than 70 percent of the terabytes shipped into enterprise organizations will be in capacity-optimized drives. This increase in demand for capacity-optimized drives is due to multiple factors:

The continuing increase in digital content and media. From consumers to the enterprise, new media, such as YouTube and Facebook, are driving production of digital applications, such as video and digital images, that require large amounts of data to be stored on capacity-optimized drives.

Disk-to-disk backup. Disk-to-disk backup is a cost-effective implementation because it eliminates the need for tape media and reduces management costs. In regards to the recovery side, disk-to-disk backup is very effective in enabling organizational productivity by reducing recovery times and application downtime.

Data retention. Organizations are retaining data longer than they may have in the past due to industry regulations as well as their own compliance standards. These organizations are finding that cost-per-GB is decreasing, so they retain their data longer because it is more cost-effective.

Virtualization. Virtualization is now considered a mainstream technology for improving efficiency and resource utilization. There is a strong correlation between virtualization and storage as growing server demands fuel storage growth. As virtualization grows, so does storage.

For the most part, Serial ATA (SATA) drives have been the answer to meeting the requirements of secondary data by offering high capacity at a low price tag. For years, organizations have relied upon SATA drives to cost-effectively store the bulk of their non-business-critical data primarily because it was the only drive type offering these characteristics. While SATA has been sufficient to date, another serial-based drive technology is making inroads that can satisfy the same data requirements but with improved performance, data integrity, and reliability – all without additional cost. This drive technology is Serial Attached SCSI (SAS). Already well established in high-performance drive markets, SAS is now penetrating in secondary storage tiers with capacity-optimized drives.


The market is ripe for the advantages and value that capacity-optimized SAS drives have introduced. These drives provide numerous benefits that strongly position them as the capacity-optimized enterprise drive of the future from the entry-level to the enterprise. Nearline SAS drives offer the following benefits:

Cost-Effective Drives

While capacity-optimized SAS drives offer multiple improvements and new functionality over SATA drives, a higher price tag might be expected; however, this is not the case. The adoption of SAS has driven costs down, and SATA drives and SAS drives now have a minimal cost difference. At the drive level itself, based on current street pricing, there is minimal price premium for capacity-optimized SAS.

Capacity-optimized SAS drives also contribute to lower costs at the system-level. By removing the requirement for additional interposer hardware that is needed for storage systems to house SATA drives, not only is an additional cost eliminated, but reliability is improved, with fewer components that could potentially fail.

Storage Performance Council (SPC) Benchmark Results

SPC-2 Results. Although capacity and price are often the leading decision factors for capacity-optimized drives, higher performance and quicker access to data are very desirable features. Capacity-optimized SAS drives offer a significant improvement in performance over SATA drives in both throughput and IOPs primarily due to their full duplex, bi-directional I/O capabilities. Published Storage Performance Council (SPC) benchmark results demonstrate this feature with up to 64 percent improvement in the SPC-2 benchmark (based on multiple workload testing).

SPC-1 Results. Capacity-optimized SAS drives perform 50 percent to 64 percent better than SATA drives and result in up to a 37 percent improvement in the SPC-1 benchmark (primarily based on applications focused on IOP operations). Capacity-optimized SAS drives also offer the best price (based on current list pricing) and performance drive for large, random-based files. If response time is important, capacity optimized drives also provide an 18 percent to 37 percent better response time than SATA drives.

Reliable/High Data Integrity

Failure is no longer an option in today’s relentless storage environments because organizations rely on information to remain productive and competitive. Like SATA drives, capacity-optimized SAS drives deliver a low Mean-Time-Between-Failure (MTBF) of 1.2 million hours and an Annualized Failure Rate (AFR) of under 0.73 percent, providing the reliable data access demanded of enterprise storage solutions today. Additionally, SAS drives deliver data integrity by reducing data corruption with end-to-end initiator-target nexus checking (IOECC/IOEDC), which helps ensure that data traveling to or from the drive is not misdirected. SATA drives lack the native addressability required to perform this function. SAS drives help decrease storage system failure rates by reducing the number of physical interconnects and adding dual-port redundancy for fail-over while eliminating a single point of failure of the additional hardware for SATA that is no longer needed for capacity optimized SAS drives.

With future support for T10 PI (Protection Information), capacity-optimized SAS drives will be a key component of an industry standard for end-to-end data integrity. This improves reliability by reducing silent data corruption events, detecting data corruption before data is written to disk, as well as isolation of the device causing data corruption.


All drives will inevitably be out of an IT administrator’s control, through theft, off-site service or repair, or disposal of old drives. Offered with drive-level encryption, self-encrypting SAS drives (SEDs) provide for comprehensive data security that protects data throughout the drive’s life cycle without sacrificing storage system performance or ease of use.

Page 2: Capacity-Optimized Nearline SAS Drives Challenge SATA

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Solid Investment Protection

Capacity-optimized SAS drives are supported with a strong roadmap to help assure organizations that capacity-optimized SAS drives can effectively keep pace with their data growth. With data retention requirements growing exponentially, capacity-optimized SAS drives are set to release increasing capacities over the coming years. Today’s capacities for 3.5-inch drives range from 250GB to 2TB. By the end of 2010, 3TB drives can be expected in the 3.5-inch form factor. With the growing popularity of 2.5-inch drives in the enterprise, these capacities are also increasing. In 2010, 2.5-inch drives are expected to offer capacities of up to 1TB. Contributing to this growth is the widespread adoption of SAS in the enterprise. IDC predicts that 70 percent of all enterprise drive shipments will be SAS by 20111 (IDC Worldwide Hard Disk Drive 2009-2012 Forecast: Navigating the Transitions for Enterprise Applications IDC Doc #216394 February 2009). While the majority of these drives today are of the 6Gbps SAS generation, the SCSI Trade Association has already added 12Gbps solutions to the industry roadmap for the 2013 timeframe.

SAS Roadmap
Low Power Consumption

One of the reasons that 2.5-inch drives have exploded onto the scene is the concern for energy efficiency in the data center. Small Form-factor (SFF) drives conserve energy by reducing power and cooling on average up to 70 percent over traditional 3.5-inch drives. In addition to lowering the Watts/GB, the smaller footprint allows more drives per system for greater performance density and redundancy.


The need for capacity-optimized drives is clear, based on the markets’ increasing need to store their secondary data cost-effectively. While SATA technology has been the leading option for years as the only capacity-optimized drive in the market, the introduction of capacity-optimized SAS drives provide multiple benefits and compelling reasons to be considered as the capacity-optimized drive-of-choice. SAS is designed and engineered for high availability, enterprise-class data storage where performance, reliability, and data integrity are paramount. With the introduction and adoption of SAS in the traditional capacity-optimized market segment, customers can now be confident that their secondary storage also meets the demanding criteria that enterprises demand.

Gina Geisel is the product marketing manager for the SAS-based storage arrays of LSI’s Engenio Storage Group. In her current role, Gina is responsible for generating collateral material, positioning literature and sales tools which are leveraged by LSI as well its OEM and channel partners. Gina joined LSI in 2006 and has more than nine years of storage experience.

John Szantho has been in product management within LSI’s Engenio Storage Group for more than six years and has more than ten years of storage industry experience. As the product manager for hard disk drives, SSDs and storage enclosures, John is responsible for helping define product roadmaps, developing market and product requirements, and championing products through development.

Barbara J. Craig is a senior product marketing manager on Seagate’s Enterprise Storage team. With more than 30 years in technology, she has spent the last 13 years focused on storage and storage networking. She attended the State University of New York, Pepperdine University, and Vanderbilt University.

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