Seagate and Western Digital are the two last big American names standing in the hard drive market, along with Toshiba in Japan, and all three face an existential thread in the SSD. More and more laptops are shipping these days without a hard drive in them, every smartphone and tablet has flash storage and Apple is sending the iPod Classic, the one with a 160GB drive in it, to the glue factory.

So what are hard drive makers to do? Find a new raison d'etre, that's what. Seagate is betting its luck on hybrid drives that combine a large SSD cache with an HDD, while Western Digital is looking at massive drive capacities and betting that the advent of cloud storage will make people buy big.

With so much of our lives becoming digital, mass storage is important. NAS devices take up a huge amount of space at the local Fry's Electronics, and there are more than two dozen cloud storage providers to choose from.

PCs were limited in drive capacity due to the legacy of the old BIOS. Thanks to that 1980 design, a PC could not physically see more than 2.1TB of storage. With the advent of UEFI, we have shattered that limit, and PCs can handle 3TB drives or larger as they hit the market. Many of the NAS devices that could hold 10TB or more use their own hardware and software fixes to get around that problem for old PCs.

But just as HDD makers hit the 3TB barrier, they started hitting physical limits of hard drives as well. WD has been at the forefront of high-capacity drives, and it came up with an interesting solution: helium.

The company on Monday introduced a 6TB drive called the Ultrastar He6 that packs seven platters into the space usually filled by five. The helium inside the drives keeps them from overheating and minimizes the friction of the heads as they move over the platters. The helium means less drag by the platters than from air, so the platters could be closer together and the motors don't have to burn as much energy spinning them.

The new drive runs quieter and consumes 23% less power when idle. It has to be hermetically sealed to keep the helium in, something the company said was a major challenge. It will be interesting to see how customers use the drive, since there are very few drives on the market that are hermetically sealed.

This means a lot of scalability over the old max of 4TB in a 3.5-inch form factor. After all, you are talking about a 50% improvement in capacity in the same space with less power drawn. So you can take up less space, or more likely deploy more storage.

It's no accident Netflix was offering a canned quote in the press release for this announcement. With so much of its content on-demand now, it needs more storage capacity, which the He6 gives.

WD has not given out the price, but the Ultrastar 7K4000 4TB model is $315 from Amazon, so expect the He6 to be a fair amount above that.