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Big HDD Showdown: Seagate 10TB vs. HGST Ultrastar He10 vs. WD Gold 8TB

HGST Ultrastar He10 10TB HDD

The HGST Ultrastar He10 features up to 10 TB of capacity and the third generation of the HelioSeal architecture, which is the company's proprietary sealing method. The He10 comes in both 12 Gb/s SAS and 6 Gb/s SATA flavors and includes an 8TB option that supplants the previous-generation He8. HGST continues to employ PMR and uses media caching technology to boost random write performance.

He10Ultrastar He10 10TBUltrastar He8 8TB
InterfaceSAS / SATASAS / SATA
RPM7,200 RPM7,200 RPM
Sustained Transfer Rate 249MB/s225MB/s
Average Latency4.16ms4.16
Operating Power6.8W (SATA) / 9.5 (SAS)6.5W (SATA)
Idle Power5.0W (SATA) / 5.8 (SAS)4.5W (SATA)
Cache Buffer256 MB256 MB
Workload Rating550 TB/Year550 TB/year
MTBF (Million Hours)2.52.5
UBER Rating1 in 10^151 in 10^15
Warranty5 Years5 Years
Weight660g660g

The 7,200-RPM drive comes with 7 platters and 14 heads for the 10TB model in an implementation that the company refers to as the "7Stac architecture." The 8TB model features 7 platters with 12 heads.  The 10TB model has a substantially higher sustained data transfer rate than the 8TB model. HGST rated the drive for 600,000 load/unload cycles, which is a key metric for heavy-use environments. The He10 features a 2.5 million hour MTBF, which is the new standard for helium drives, and a five-year warranty. The drive comes with Instant Secure Erase (ISE) and Self-Encrypting Drive (SED) options and features an 816Gbits/in2 areal density.

The 10TB 12Gb/s SAS models consume more power than their 6Gb/s SATA counterparts do, but that is a common occurrence for the dual-ported SAS connection.

HGST led the market with its new media caching technology, which debuted in its 10K and 15K HDDs, and then moved the technology into its high-capacity offerings. Seagate followed with its own technique, which varies architecturally but has the same end result.

HDDs use DRAM to cache incoming data, but DRAM is volatile, which means that during an unsafe power loss all of the data in DRAM will be lost. Volatility limits the amount of caching that the vendors can do safely, but HGST's media caching technology provides power-safe random write caching by persisting data on reserved sections of the platter.

HGST created small caching zones on the HDD, which boosts performance by limiting head movements during write operations. The HDD replicates the data held in the DRAM buffer to these zones, which provides the HDD with a copy of all the data in the cache in the event of an unsafe power loss. The process allows the HDD to conduct more efficient write combining, which is the concatenation of multiple small random writes, before passing the data down to the platter for final storage. This technique greatly enhances the HDDs random write performance and provides one of the largest jumps in mixed workloads in recent history. Unlike some caching techniques, the cache never becomes full, so the drive can continue to offer the higher level of performance for an unlimited amount of time. We have a more thorough explanation of HGSTs media caching technique here.

HGST was the first vendor to ship helium drives, and as such, it continues to lead the market in volume shipped with over 4.25 million units as of December 2015. The number of helium units compared to the number of air-based HDDs remains small, but the high-density focus of the helium drives means that they accounted for over 25 percent of all exabytes shipped last year (according to HGST data).

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The HE10's sealed case leaves most of the internals to the imagination, though we spot the key components when we remove the PCB from the body of the drive. A blue foam pad reduces vibration between the two components, while a small thermal pad over the controller wicks heat into the body of the drive, which acts as a large heatsink. The He10 utilizes standard surface mount-points to connect with the PCB, while the previous generation He8 series employed pins to connect the two components.

Paul Alcorn

Paul Alcorn is the Deputy Managing Editor for Tom's Hardware US. He writes news and reviews on CPUs, storage and enterprise hardware.