Hard disk drives or HDD, are commonly used devices in PC, Laptops, servers and more. They are used to store large amount of information. We can find HDDs on the marked that offer 500GB, 1TB, 2TB and larger. They can also be combined, so you can have a large storage device inside your computer.
What are the components of a hard disk drive
The hard disk drives are made with few main components, which help them achieve their task, which is to store a large amount of data. They consist of:
- Spindle – this is the place where the platters are mounted
- Actuator – this part is used to control the movement of the read-write head.
- Platter – this is the disk part of the device, it is flat and resembles a CD disk. It is made of metal and it stores the data.
- A circuit board – this is the place of the device that is connected to the interface cables and power.
How do HDDs store data
The information is stored on the platter, which is made of metals. Its top layer is made with a ferromagnetic coating. It contains the data. The HDD stores all the information digitally, or in 0 and 1. Binary (a counting system containing zeroes and ones) is used by digital devices to store, process, and show information.
The CPU has components that act as switches, so ON would represent 1 and off 0. The hard disk itself doesn’t have these types of elements. Instead, it uses the polarity of magnetic fields to store the information on the ferromagnetic layer on the platter of the HDD. The hard disk platter’s layer has sectors that can be either + or -.
The disk has many sectors and some hard disks have two disks so more sectors are available. The platter spins and so the reading head reads the magnetic sectors and delivers the information to other parts of the computer. Hard disks store the information without the need for electricity as the fields are constant until you download or create a file and it needs to write some information on the platter.
How do HDDs work
Hard disk drives write and read the information on the platter. They can do that by spinning the disk, which has the information on it, and by using the read/write heads that go over it. They need a power source, which they get from the computer’s PSU. They are connected to the motherboard which transferred the information from the HDD to the other components of the PC.
When you open a file, for example, the hard disk’s read head goes over the sectors and checks the information, which is stored in + and – . It then transfers the information to the motherboard and other components of your device, then the CPU calculates and sends instructions to other components such as the graphics card, which sends the digital data to your monitor which shows the file’s contents.
What is HDD cache
Since there can be terabytes of information on the disk, it can have millions of sectors, as the disk is spinning it can take some time to access a file. HDDs have microcontroller which transfers and keeps data that is cached. An HDD cache is used to speed up the disk. Many of the HDDs use caches from 8 to 256MB, which might not seem a lot, but it is because cached data is not often used again. The cache stores information that you frequently use, which reduces the response time of the device.