Normally, hard disk drive units have four platters inside them and, in rare cases, five, but Western Digital has come up with a way to incorporate seven inside a single storage unit.

Technically, seven platters fit well enough inside a hard drive. The problem lies in warping when spinning at high rates, and the friction that the air subjects the platter to.

That is why WD has decided to replace the air with helium. Sure, it means it will have to perfectly seal the HDDs against the outside world, but that's a minor sacrifice when a 3.5-inch HDD can suddenly pack a capacity of 7 TB.

This should remove the pressure that researchers have been feeling lately, as they were forced to step up their efforts to increase the areal density of said platters.

Lower platter friction is actually a secondary benefit in all this too. The real advantage lies in the reduced fluid flow forces buffeting the arms that position the heads over the data tracks. That's why the disks can be placed closer together.

Lower shear forces and more efficient thermal conduction don't hurt either. They make the units cooler and more silent.

“We are currently sampling these products with selected customers right now,” said Stephen D. Milligan, chief executive officer of Western Digital, during the latest conference call with financial analysts.

“We continue to expect that we will have units shipped and revenue realized before the end of the calendar year. The first generation product will not be a particularly significant volume product to start out with as customers test it out and that sort of thing.”

HGST (formerly known as Hitachi) will be the division tasked with shipping helium-filled seven-platter hard disk drives this year (2013). Right now, only samples are being shipped, and even the first wave of actual units will be more geared towards testing, but it's a definite step forward.

Overall, the new sealed HDDs will have 45% better watts-per-TB rating, and 23% less energy need.