Data Recovery and Hard Drive Components

A hard drive, to most of us, just looks like a rectangular device which stores our data. We don`t know how it works, just that all of our precious information is in there somewhere. To get a better understanding of what goes on inside, how they work, and how to recover the data when they stop working, let`s look at a hard drive from the inside.In order to make the article more relevant we will use a new 1TB Western Digital 3.5" hard drive and open it up. The main enclosure, usually black or silver, is what the everyday computer user will know to be the hard drive. It is actually called the hard disk assembly, or HDA. The top side of the HDA is covered by the top cover with a sticker detailing information about the hard drive such as manufacturer, capacity, model, serial number etc.The underside of the hard drive houses the printed circuit board, or PCB. This is the green electronic board which covers about half of the underside of the drive. The components of the PCB are usually on the inner side of the PCB, protecting them from damage. On the underside the cover for the motor spindle can also be seen.SATA drives have 2 connectors. The small connector carries data to and from the drive, whilst the larger is the power connector for 5v and 12v lines. On the PCB are 3 main components. They are the main controller unit, motor controller and onboard memory or cache. The MCU is equivalent to the processor (CPU) of your computer, essentially the brains and computing power of the drive. The motor controller performs the function of spinning up the platter/s inside the drive, and controlling the movement of the voice coil which directs head movement. The memory chip is like the RAM in your computer. It is labelled as `cache` in the hard drive world and stores data being written to, or read from, the drive. The contacts for the heads and motor can also be seen. The ROM information is also found on the PCB and is usually found on an 8-pin IC (chip), other times this information is stored in the MCU itself. The ROM contains a portion of the firmware required to start the hard drive recovery, with the rest of the firmware being read from the drive platter itself.From a data recovery perspective, sometimes the PCB will fail from a power surge or physical damage. To recover the data the PCB will have to be repaired or replaced, but this is not a straightforward process.