Tuesday, July 28, 2020

After A Decade, HAMR Is Still Nearly Here

At the 2009 Library of Congress workshop on Architectures for Digital Preservation, Dave Anderson of Seagate presented the company's roadmap for hard disks He included this graph projecting that the next recording technology, Heat Assisted Magnetic Recording (HAMR), would take over in the next year, and would be supplanted by a successor technology called Bit Patterned Media around 2015.

I started expressing my gradually increasing skepticism the following year. Now, nearly eleven years after Dave's talk, it is time to follow me below the fold for another update.

At last year's Library of Congress workshop on Architectures for Digital Preservation Seagate reported that:
Seagate is now shipping HAMR drives in limited quantities to lead customers
But volume shipments were, as they had been for a decade, "next year".

Last February, Jim Salter's HAMR don’t hurt ’em—laser-assisted hard drives are coming in 2020 provided an update both on Seagate's progress:
Seagate has been trialing 16TB HAMR drives with select customers for more than a year and claims that the trials have proved that its HAMR drives are "plug and play replacements" for traditional CMR drives, requiring no special care and having no particular poor use cases compared to the drives we're all used to.
In September last year Chris Mellor's Western Digital debuts 18TB and 20TB near-MAMR disk drives reported on Western Digital's progress with its rival Microwave Assisted Magnetic Recording (MAMR) (my emphasis):
Western Digital has announced 18 and 20TB disk drives using a partial microwave-assisted magnetic (MAMR) recording technology implementation (ePMR). Sample shipments are due by the end of the year.
The Ultrastar data centre DC HC550 is a helium-filled drive in 16TB and 18TB versions. It uses either 8 or 9 platters and has conventionally recorded tracks. The drive implements a form of energy-enhanced perpendicular magnetic recording (ePMR) which has not been explained.

The 20TB DC HC650 has 9 platters and uses shingled magnetic recording (SMR), with zones of partially overlapping tracks, to cram in an extra 2TB of capacity over the HC550.
Jim Salter's Western Digital releases new 18TB, 20TB EAMR drives provides an update on availability:
Earlier this month, Western Digital announced retail availability of its Gold 16TB and 18TB CMR drives, as well as an upcoming 20TB Ultrastar SMR drive. These nine-platter disks are the largest individual hard drives widely available today.

Earlier this year, rival drive vendor Seagate promised to deliver 18TB and 20TB drives in 2020, but they have not yet materialized in retail channels.

Seagate's largest drives, like Western Digital's, needed a new technology to overcome the Magnetic Recording Trilemma—but Western Digital's EAMR (Energy Assisted Magnetic Recording) is considerably less-exotic than the HAMR (Heat Assisted Magnetic Recording) used by Seagate. That more conservative approach likely helped Western Digital beat its rival to market.
He also provides the explanation of what "ePMR" is, and makes it clear that it isn't actually "near-MAMR":
Although Western Digital is continuing its research into MAMR technology, the tech used in this month's new drives—EAMR, or Energy Assisted Magnetic Recording—is considerably less exotic. Rather than alter the magnetic properties of the medium with microwave or laser emissions, EAMR simply stabilizes the write field more rapidly and accurately, by using a bias current on the main pole of the write head as well as the current on the voice coils.
The key point here is that heads are hard. HAMR requires a new head design to include the laser, and MAMR requires a new head design to include the microwave generating "spin torque oscillator", but EAMR is a tweak on an existing head design. So it is "considerably less exotic" technology.

As Jim Salter wrote:
Seagate has been working on HAMR for a long time; the company's first big press release about the technology came in 2002.
Western Digital hasn't been working on MAMR for that long. It only became clear that they had given up on HAMR in 2017, with Chris Mellor's Western Dig's MAMR is so phat, it'll store 100TB on a hard drive by 2032:
WDC has given up on heat-assisted magnetic recording (HAMR) and is developing a microwave-assisted technique (MAMR) to push disk drive capacity up to 100TB by the 2030s.
Note the claim in Western Digital's marketing slide "1st product anticipated in 2019". It is midway through 2020 and they're just shipping a stopgap on the way to MAMR. And Seagate has yet to ship volumes of HAMR drives. Both are still probably "next year". As I wrote a year ago:
Industry projections should always be taken with many grains of salt, as my earlier posts about the good Dr. Pangloss indicate.

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