The 6TB Ultrastar He6 drives are helium filled units based on HGST’s HelioSeal technology. They partly owe their large capacity to the fact that the firm has managed to cram seven disk platters rather than five into the standard 1in high form factor for 3.5in drives.
HelioSeal sees the air inside the hard drive replaced with helium, which is less dense and so reduces the turbulence caused by the spinning disks, cuts power consumption and leads to reduced frictional heating, according to HGST.
A side effect of this is that the drive is hermetically sealed, opening up the possibility of the Ultrastar He6 drives being able to support being submerged in non-conductive fluid for liquid cooling applications. The Ultrastar He6 line is available in versions with either a 6Gbps SATA or 6Gbps SAS host interface, with a quoted mean time before failure (MTBF) of 2 million hours, according to HGST.