How your hard drive works

Hard drives are truly remarkable. They can store gargantuan amounts of data which we rely on every day (hard drive recovery is a service that's always in demand) and do so by using a combination of two things: magnets and binary.

Within every hard drive is one or (and this is much more likely with modern hard drives) multiple platters. These are disks made from materials such as aluminium and are coated with a thin layer of metal that is capable of being magnetised.

Every platter within a hard drive also has both a read and a write head. As their name suggests, write heads are used to write data on to platters and read heads to read it. But how?

Each platter contains billions of microscopic areas that can be either magnetized or de-magnetized, with a magnetized area representing a 1 and a de-magnetized area representing a 0. Each of these individual areas are called bits and, when you store a piece of data – whether it be a word document, photograph or video file – this is translated into binary and successive areas of the platter are magnetized and de-magnetized accordingly.

To put it another way, the letter ‘a’ becomes 01100001 in binary so, to store this, a hard drive’s write head would de-magnetize one area, then magnetize the next two, then de-magnetize four and then magnetize one. When this file is then opened the drive’s read heads can see these ones and zeroes and feed the information through to a programme which will translate it and open the file.

Whilst this explains how hard drives store and read data, though, it does not address one very big problem: how do you then find where it’s stored?

As we’ve discussed previously, each of a hard drive’s platters is comprised of billions of different areas. Imagine looking for a single specific item within a library that contained billions of books but had no filing system. You’d never be able to find what you were looking for! That’s why hard drives write data in an orderly fashion.

When someone stores a file, a hard drive writes the data in an uninterrupted concentric line known as a track. Tracks are also broken down into smaller areas know as sectors.

A file on every hard drive records the location of these tracks and sectors as well as those which have not yet been used. This file is then accessed whenever something is stored on or retrieved from the drive in order to determine the data’s location or a suitable location for new data according to the user’s instructions.

Sadly, hard drives are prone to what are commonly referred to as a head crash. Read and write heads are sensitive and if a small particle finds its way into the drive, it can disrupt their movement causing them to strike the platter and render the data unreadable.

If your hard drive has suffered a head crash and need to be repaired, get in touch with Fields Data Recovery today.


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