Seagate, after hinting in May that it would release 8TB and 10TB hard drives in the next 12 months, has started delivering early samples of its 8TB hard drive to “major customers” (i.e. enterprise customers). Curiously, while Western Digital hit 6TB last year by filling its drives with helium, Seagate appears to be pushing the 3.5-inch spinning disk storage envelope by simply increasing areal density. Western Digital, incidentally, despite being the first to 6TB, hasn’t announced anything new since November 2013. Maybe helium wasn’t quite ready for prime time?

During Seagate’s quarterly earnings call, CEO Steve Luczo spoke about all of the company’s major efforts — including its recent move into 6-, 8-, and 10-terabyte drives. Seagate officially announced its 6TB non-helium-filled drive in April 2014, and Luczo says that, “In the enterprise market, most of our major OEMs and cloud customers are qualified or are actively qualifying” the drive. With the 6TB done and dusted, attention has moved to even larger drives: “We have also delivered 8 terabyte customer development units to major customers and cloud service providers and the initial customer feedback has been very positive.”

What’s missing from the earnings call, however, is any mention of when these hard drive behemoths are coming to the consumer market — and, more importantly, how exactly Seagate is reaching such incredible storage densities. [Read: How long do hard drives actually live for?]

In Western Digital’s 6TB drive, the use of low-density, low-resistance helium allowed the company to squeeze seven platters into a standard-height 3.5-inch hard drive. Seagate, without the hermetically sealed helium tech, had to stick to six platters, with a massive areal density of 1TB per platter. For the 6TB drive, we believe Seagate used conventional perpendicular magnetic recording (PMR) rather than shingled magnetic recording (SMR) or heat-assisted magnetic recording (HAMR).

But how did Seagate squeeze 8TB into a normal 3.5-inch drive? Seagate, rather annoyingly, is keeping schtum on the matter. It seems unlikely that Seagate could’ve upped its areal density from 1TB to 1.3TB per platter in just a few months without deploying a new recording technology. It is also possible that Seagate managed to squeeze seven platters into the enclosure, despite the lack of helium, along with a smaller bump in areal density to 1.14TB per platter. [Read: How a hard drive works.]

In either case, we are probably looking at the semi-secret deployment of shingled magnetic recording to reach higher per-platter densities. Back in 2013, Seagate said it was already shipping SMR-enabled drives, but actual data on which drives actually use SMR is hard to come by. Curiously, a data recovery company only just announced that it had become the first in the world to recover an SMR drive (due to the recording tracks being overlapped like shingles, the tools required to recover the data need to be recalibrated).

SMR is theoretically a lot slower than PMR when it comes to writing data, but there doesn’t seem to be much empirical data to support that.

The other possibility is HAMR, which uses a small laser on the hard drive’s write head, allowing for a massive increase in areal density Seagate has mooted the prospect of 10 terabits per square inch — current PMR hard drives generally have an areal density of a few hundred gigabits per square inch. While HAMR is due to hit the market any day now, I suspect Seagate would be making a rather large fuss if it had created an 8TB or 10TB HAMR drive.