Seagate: Hybrid Drives Don’t Need More Than 8GB Of NAND

According to recent research by Seagate, a hybrid Solid State Hard Drive (SSHD) needs just 8GB of NAND memory to provide performance levels similar to those of a pure-bred Solid State Drive (SSD).

Seagate launched the industry’s first hybrid drive, Momentus PSD, way back in 2007. The company currently sells a range of third generation laptop SSHDs, and desktop models with capacity of up to 4TB are due to launch in the next quarter. However, all of them will be limited to just 8GB of fast NAND memory.

Seagate says that during its tests, a typical work computer accessed just 9.59GB of unique data a day, so 8GB would be enough to store most of it on Flash and dramatically improve performance.

The future is hybrid

According to research presented during a technical workshop in London on Tuesday, just 2.11GB of Flash memory will allow a PC to achieve 95 percent performance of a full SSD system. During the five days of study, the average amount of data read by machines in a business environment stood at 19.48GB. Out of this amount, just 9.59GB was unique; the rest consisted of duplicate reads.

The study essentially proves that, at least in the workplace, any amount of NAND memory larger than 10GB would have a limited impact on performance. Of course, data-intensive tasks like analytics or video rendering, where fresh data is being accessed all the time, would benefit from larger amounts of faster memory, but an average user is unlikely to notice the difference between SSD and SSHD. “We think that in the future, all hard drives will come with a bit of NAND,” Rob Dixon, sales manager at Seagate told TechWeekEurope.

Just like SSDs, SSHDs can considerably speed up boot times and improve application responsiveness, but they do it at a fraction of the price, while offering a lot more capacity. What makes this possible is the ability of SSHDs to learn how to separate information into ‘hot’ frequently accessed data and ‘cold’ data, which can remain on the mechanical part of the drive. Since reading is biased towards Flash and writing towards the disk, the method also minimises wear and tear, increasing lifetime of the drive.

Seagate is so confident in its hybrid offering it is actually stopping production of high-end 7,200 RPM hard drives for laptops at the end of 2013, with the remaining models spinning at 5400 RPM. Instead of the faster mechanical drives, Seagate is focusing on SSHDs, which can visibly improve performance but cost just 20 to 25 percent more than their spinning disc cousins.

Additionally, any technological breakthroughs in hard drive manufacturing could be easily applied to SSHDs. Seagate is currently working on a technique called Shingle Magnetic Recording (SMR), which allows to squeeze more tracks onto a disk surface by partially overlapping them. SMR depends on the same HDD hardware components, but requires specialised software, and should help mass-produce drives that break the 1TB/in² barrier.

By 2015-2016, Seagate hopes to launch hard drives that feature Heat-Assisted Magnetic Recording (HAMR). With HAMR, the recording head includes a tiny laser that heats up the medium before information is written, to allow the use of smaller magnetic grains and narrower data tracks. The technology was successfully demonstrated last year and could take information density to unbelievable 5TB/in², but there are still plenty of kinks to iron out.

The excitement around hybrid drives doesn’t mean Seagate will stop working on pure SSDs. Earlier this year, the company announced four drives to spearhead its new Flash strategy, including consumer-friendly 600 SSD and 600 SSD Pro models, enterprise-grade 1200 SSD, and even a superfast Flash PCIe appliance for the data centre developed jointly with its partner Virident, the X8 Accelerator.

To manufacture the new products, Seagate buys Flash memory from Samsung, a company which also markets its own SSDs, making it a direct competitor. Whether this unusual partnership will last, remains to be seen.

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