By Karim Salmi / Data Recovery / 0 Comments

How Hard Drives Save and Retrieve Your Files

Article 4: How Hard Drives Save and Retrieve Your Files

Bonjour! In this fourth installment of the VitalTech hard drive and data recovery blog series we’re going to cover the basics of hard drive file saving and retrieving to give you a better understanding of how it works. While you may think files are nicely and neatly saved in tidy Matrix-like cubes, it’s actually a bit more interesting than that.

Other Articles in This Hard Drive and Data Recovery Series

Note: Feel free to use the hyperlinked titles below to move through the series in your own way and at your own pace.

Article 1: Your Hard Drive (How It Works and What Causes It to Crash)

Article 2: The Basics of Modern Hard Drive Disk Failures

Article 3: Hard Drive Mechanical Arm Failures 101

Article 4: How Hard Drives Save and Retrieve Your Files

Article 5: Hard Drive Printed Circuit Boards and Data Recovery Explained

Article 6: An Intro to Internal Hard Drive to PC Connections

Article 7: External Hard Drives and Data Recovery

From original hard drives in the 50s like the gargantuan IBM RAMAC 305, to modern versions that can fit in your back pocket as thin as a pancake yet possess enough capacity to hold hundreds upon hundreds of CDs worth of music files, videos, images, and more…we’ve come a mighty long way.

internal view of a hard drive platter

All of that computing evolution sits on a foundation of magnetism and bits, or binary digit sequences of 0s and 1s that are then divvied up into billions of sectors on your hard drive disk (HDD) platter. So even when the computer isn’t on, or the data is on an inactive external drive or device, it’s still there embedded into a magnetic plate.

A Closer Look at Hard Drive Disks

Made of hard glass or aluminum and coated on each side with an extremely thin layer of metallic material capable of being (de)magnetized, the hard drive disk is where all the data is stored and retrieved.

Remember we’re talking billions of microscopic bits of binary code spread out all over the disk, which is why it has to spin so fast, up to 10,000 RPMs to allow the read-write head and mechanical arm to instantly access it. That said, the vast majority of the work isn’t writing the data, but retrieving and filing it.

Let’s talk about how your data is saved. There’s basically three parts.

  1. Tracks: As the plate spins in a clockwise motion, data-bits are arranged in concentric patterns or pathways which like on a music record or CD are called tracks.
  2. Sectors: Tracks are then further broken down into much smaller sectors or specific areas, some grouped together.
  3. The FAT: Finally, the computer meticulously keeps a map of data, and each sector, so it knows what space is used and what’s open for new information.

Just try and imagine what happens when even one speck of dust happens to lands on and sticks to the plate. Then let’s say that speck causes the read-write head to bounce and then make contact with the plate when it comes down. Even one tiny scratch can impact hundreds if not thousands of files.

Sometimes signs of disk problems are noticeable, if you’re lucky, but oftentimes disk crashes just happen…boom! That’s where VitalTech comes, to run diagnostics, check software for corruption, inspect the mechanical components and take care of hard drive data recovery.

Now that we’ve taken a gander at how hard drive file saving and retrieving works, in our next article of we’ll look at the printed circuit board which acts as the central nervous system of your hard drive.

A computer guru with ten years of professional experience. From corporate IT to forensic data recovery, he has seen it all and has the stories to prove it. His hobbies include programming and ice hockey.