But yeah. 4TB HDD's are good. Nobody with half a brain is going to be buying the first generation of them though.
Hitachi and Hitachi Global Storage Technologies (Hitachi GST) announced today they have developed the world’s smallest read-head technology for hard disk drives, which is expected to quadruple current storage capacity limits to four terabytes on a desktop hard drive and one TB on a notebook hard drive.
From GMR to TMR to CPP-GMR
The discovery of the giant magnetoresistance (GMR) effect occurred in 1988, and that body of work was recognized just last week with a Nobel Prize for physics. In 1997, nine years after the initial discovery of GMR technology, IBM implemented the industry’s first GMR heads in the Deskstar 16GXP. GMR heads allowed the HDD industry to continue its capacity growth and enabled the fastest growth period in history, when capacity doubled every year in the early 2000s.
Tunnel magnetoresistance (TMR) effect at room temperatures was discovered back in 1995 and was used to create heads for hard drives featuring perpendicular magnetic recording starting from 2005.
The recording head and media are the two key technologies controlling the miniaturization evolution and the exponential capacity growth of the HDD.
Cutting Through the Noise
The continued advancements of HDDs requires the ability to squeeze more, and thus, smaller data bits onto the recording media, necessitating the continued miniaturization of the recording heads to read those bits. However, as the head becomes smaller, electrical resistance increases, which, in turn, also increases the noise output and compromises the head’s ability to correctly read the data signal.
High signal output and low noise is what is desired in hard drive read operations; thus, researchers try to achieve a high signal-to-noise (S/N) ratio in developing effective read-head technology. Using TMR head technology, researchers predict that accurate read operations would not be conducted with confidence as recording densities begin to surpass 500Gb/inch?.
The CPP-GMR device, compared to the TMR device, exhibits less of an electrical resistance, resulting in lower electrical noise but also a smaller output signal. Therefore, issues such as producing a high output signal while maintaining a reduced noise to increase the S/N ratio needed to be resolved before the CPP-GMR technology became practical.
In response to this challenge,
Recording heads with 50nm track widths are expected to debut in commercial products in 2009, and those with 30nm track widths will be implemented in products in 2011. Current TMR heads, shipping in products today, have track widths of 70nm.