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How do Hard Disk Drives (HDDs) work anyways, and how have they gotten better over the years?
TLDR: A hard drive stores information on a small electronic device, the key components inside are a magnetic platter, a writer head, and a reader head. The writer changes magnetic field direction of very small sections of the platter which when read create a magnetic field that can either be interpreted as a 1 or a 0. A string of those bits equal a byte that can be read as a letter or number, thus allowing for the creation and storage of information. The density at which the magnetic grains or domains can be created results in the storage capacity of the hard disk drive (HD
Each hard disk drive (HDD) is comprised of
A magnetic platter in which data is written to and
The spindle that keeps the platter in a position
readable by the reader and rotates so that the reader can continuously read the
information.
A reader head responsible for capturing an
interpreting the magnetic field read on the magnetic platter of the hard disk
drive (HDD)
A writer head responsible for writing and overwriting
magnetic grains or domains on the hard disk drive platter so that the data can
be read by the hard drives reader head.
The Actuator which is a small motor that is
controlled by the devices circuit board to ensure the movement of the read
write arm and platter to make sure that the correct information is read and
written to in the exact right place.
Miscellaneous Parts such as the casing on the outside of the hard disk drive that holds all of the pieces together, the circuit board controls input and output signals along with the external ports at the end of the drive. All drives have one port for the power to the device and one port for the transferring of data and instructions to and from the rest of the system.
Each disk or platter is coated with a microscopic coating of magnetized metal. For modern day hard drives, the magnetic alloys are typically CoPtCr (cobalt+platinum+chromium) with traces of boron or tantalum added at times to improve the stability of magnetic domains. The material needs to be very sensitive to magnetic fields.
Data is recorded as a magnetic pattern; several bits are grouped, and each group has a consistent electrical current direction written on it by an electromagnet. The magnet generates an electric field strong enough to overwrite and change the current. This is recognized by the magnetic reader head as 1s and 0s. Each group is considered a “bit”.
Groups of 1s and 0s or “bytes” can be read as letters, for instance:
A = 01000001
B = 01100001
C = 01000010
Aerial density or the amount of storage per square inch of a hard drive is the number # of bits that can fit on 1 sq inch.
Back in 1957 IBM created the first ever hard drive, today hard disk drives can carry an aerial density of 1 TB/sq in, ovwe 500 million times greater than the first ever hard drive. Several iterations of technology occurred between 1957 and today for us to get to this point. In the 1970’s we had Ferrite Inductive Read/Write Heads, in the 1980’s Thin Film Lithography processes led to the creation of the Thin film Inductive Read/Write Head. Thin film Inductive write Heads with MR were created in the 90s and finally, Perpendicular Thin Film Inductive Write Head GMR Read Head were made in the 2000s. The simple fact being, readers became more sensitive overtime by taking advantage of new discoveries in magnetic and quantum properties of matter.
More discoveries:
The Importance of Mathematical Algorithms – Mathematical algorithms created the ability to pack bits closer together and allow the ability to filter out noise of magnetic interference. Math algorithms also allowed magnetic readers to find the most likely bit sequences from each chunk of readback signal filtering out data noise.
Thermal expansion – Thermal expansion control of the writer head allowed (using a heater to heat the head) allowed the writer reader to hover much closer to the surface of the disk (within 5nm = 2 strands of DNA)
Heat assisted magnetic recording (HAMR) – Further, Heat assisted magnetic recording (HAMR), uses thermally stable recording medium (disk) that reduces the magnetic resistance momentarily on a particular magnetic grain utilizing lasers which allows data to be more easily written (video from 2015 claimed these are in prototype stage)
The future and beyond:
Nanosized magnetic grain particles – Separate nanosized grain structures may potentially allow for up to 20 Tbit/in2 density
Challenges with increasing hard disk drive (HDD) storage:
What can limit the storage density are many facts, among them being (a) very small domains are hard to create and read back, (b) very small domains can sometimes flip directions due to heat or noise in the environment, and (c) when very small domains are very tightly packed next to each other, their magnetic fields affect each other and one domain can flip the magnetization of a neighboring domain over time. All these problems create errors in reading and writing the binary data — so the information is damaged or lost.
Industry Standards:
There are several industry standards to specify and control transferring data back and forth between a hard disk and a computer. The most common are called IDE and SCSI.
Hard Drive Disk Destruction:
At ReTech, we understand how information is stored on a hard drive, we also understand its limitations. Proper data destruction techniques are required to properly dispose of organizational data. For example, Hard Disk Drives (HDDs) are physical devices that can experience physical damage. In cases of physical damage, overwriting or degaussing the device may not be sufficient for making information practiacably unreadable or unrecoverable. In these cases where a hard drive is damages internally, ReTech uses physical methods of destruction, such as hard drive shredding to ensure data is properly destroyed. If you are interested in certified hard drive data destruction, reach out to ReTech let us help you increase your information security.
Kyle Nelson
Kyle Nelson is an experienced information security practitioner and a proven leader of IT Operations for large organizations. Kyle Owns ReTech Data Destruction & Recycling LLC.