In the first part of this article we described the evolution of the hard disk technologies, now we will discuss the future technologies of HDD.
A new PMR- (perpendicular magnetic recording) based HDD technology
A new PMR + method of storing data on a hard disk is the Two Dimensional Magnetic Recording (TDMR) technology. This method is currently being researched by Samsung. The company has stated that it will introduce the technology in future products starting in 2017.
TDMR, which is based on the idea of perpendicular magnetic recording, is challenged when the density of the tracks increases. Track pitches are becoming smaller and the magnetic read head is wider than the actual data track width: The data signals the read head receives worsen as the data track narrows - an effect called magnetic inter-track interference (ITI). This means it becomes increasingly more difficult for HDD heads (readers) to perform read operations. In contrast to the writing heads, which can be designed smaller, read heads cannot be reduced in size.
TDMR - as the name suggests –combines multiple read heads to read a single data track. Two-dimensional magnetic recording technology uses an array of heads to read data from either one, or several nearby tracks. This enables HDD controllers to receive improved signal-to-noise-ratio data streams and determine the correct data based on input from several locations. Samsung states that using several read heads can offer the possibility to further increase the area density by an additional 10 percent compared to SMR. By combining the SMR and TDMR technologies, Seagate thinks it can increase the area density of HDD platters by about 10-20 percent versus today's traditional PMR platters.
Two advanced and non-PMR technologies are on the horizon, too!
To get data even more dense on a platter, two other methods and technologies are currently explored by manufacturers: HAMR (Heat Assisted Magnetic Recording) and BPMR (bit-patterned magnetic recording).
HAMR permits smaller bits to be written by using diode laser integrated onto the magnetic recording head to heat up the disk where data is about to be written. The laser is focused onto the disk using a near-field optical device. The small laser spot (tenths of a nanometer) heats the magnetic disk locally to make it easier to switch the magnetization direction, which is how bits are written. The heat causes the magnetic grains to lose their superparamagnetic effect for a short period, allowing for smaller magnetic grains and higher area density. When this small spot cools, the data is frozen in place and stable. Reading the data happens the same way as it is done today. HAMR could increase area density to 1.5Tbit/inch2, 50 percent higher than today's drives; enterprise drives could come in 2017 with a general availability estimated to be in 2018.
BPMR is the abbreviation for Bit-Patterned Media Recording and also tackles the density challenge: By using this method the grains sit on nanolithografically created, elevated “islands”. Without getting into too much technical detail here, the main interest is to make the grains smaller – making the one grain = one bit, a dream come true by putting a single magnetic grain onto each “island” of a bit-patterned medium and thus making the whole HDD platter even more dense.
Even though its inventor, Toshiba, is currently researching on several aspects of the BPMR technology it will be not likely to hit the market in the near future. If ever, it will be a technology to be included in products in 10-15 years.
Conclusion: What we are currently experiencing is that several technologies are developed side by side to get the most out of the magnetic hard disk drive. Some challenges of the technologies described here are far easier to tackle than others and most likely every company is eager to get its products to market as fast as they can, so their HDD business is running while being attacked by SSD vendors on the other side.
What can be said today is that some technologies will stay longer in the market than expected. For instance SMR HDDs will not go away very soon since TDMR and HAMR are currently still not market-ready. It is more likely that those technologies will be mixed in the future as they become available: For example SMR and or TDMR could be and will be used in conjunction with HAMR, while BPMR, if it is introduced, play in its own territory since most of the problems and challenges are still to be solved.
One thing is certain already: With these technologies on the horizon or ready to hit the market, data recovery specialists who work in the cleanroom have to make sure to acquire the necessary knowledge to tackle the challenges which come with these technologies. Otherwise, they will not be able to physically recover data in this increasingly atomized environment.
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