Table of Contents
What is a Hard Disk (HDD)?
A hard disk is a thin film of magnetic material applied to the platters. With a read-and-write head, the magnetic film can be read or adjusted.
Because the platter rotates in circles at high speed, the read and writes head passes the same point several times per second. The reading and disk head then also move from left to right. This allows the read and disk head to reach the data inside and outside the hard disk (platters).
The reading and writing head skims over the platters at high speed to measure the invisible magnetic differences for us. And translate this into 1’s and 0’s.
Several platters are placed in a hard disk to give hard disks more storage space. For example, in the photo above, you see three platters on top of each other, with a reading and writing head in between.
The factories are also increasingly able to store more data on a platter using other techniques. As a result, not every flatter has the same data density.
To ensure that the read and write head hang as close as possible above the platters, the new development is that hard drives are made airtight. They are then supplied with helium. The reason for this is that helium has a lower density than air.
The advantage of this is that there is less friction, and hard disks are less likely to overheat. This also makes it possible to use more platters. Hard disks can be fitted easily with seven trays for 3.5 ″ models (found on desktops). Due to the lesser friction, less energy is also needed to rotate the platters.
Hard disk speed
The speed of a hard disk can be interpreted in different ways.
1. The speed at how fast the platter is spinning
2. The speed at which the hard disk can read and write data.
Speed
There are two speeds that you encounter most often. That is 5400 RPM and 7200 RPM. This means with the 7200 RPM that, the platter makes 7200 rotations per minute. So the platter spins 120 times per second. So that is very fast.
In contrast, a 7200 RPM hard disk makes more noise and has higher energy consumption and heat. That is why you often see that 5400 RPM hard drives are used in portable computers. After all, saving energy is the most important thing with a laptop so you can use it for as long as possible without mains voltage.
Speed
The faster a platter spins, the more data it can read from the spinning platter. After all, with every turn of the platter, more data passes the read-and-write head.
But not every platter has the same data or data density. In addition, the amount of data that can be on a platter differs per manufacturer. As a result, a read-and-write head may see as much data per minute with a 5400 RPM hard disk as with a 7200 RPM disk with a lower data density.
That is why we measure the speed of a hard disk when reading and writing data in MB / s (MegaBytes per second). We estimate this for reading and writing data because there is a difference.
Speed
I gave this overview to give you an idea of
In addition, we often measure the speed of a hard disk in 3 ways. Sequentially, one after the other, from the beginning to the end of the hard disk. 4KB, small files that often read or write an operating system, and 1MB blocks of data.
A hard disk should always reach 60MB / s. Of course, with the current SATA interface. Older hard drives still use IDE, a wide flat connection cable that can handle less speed.
For comparison, an SSD can reach 600MB / s. That is ten times faster in the wrong case. That is why an SSD is also a significant improvement over a hard disk regarding speed.
Access time
Another form of speed that you can measure with a storage device is the access time. That is the time before a storage device can retrieve your requested data.
Because a hard disk contains a rotating disk, this always takes 8.3 ms. Because with a hard drive with a platter that runs 7200RMP, it takes 16.6ms before it has had a complete rotation. An average hard disk access time is, therefore, often 16ms.
For comparison, the access time of an SSD or eMMC memory is almost 0ms! So the computer can (almost) immediately retrieve the data from the chip. And you don’t wait until the reading head is in the correct position on the platter.
Future of the HDD
Solid-State Drives (SSDs) with large storage capacities are not yet affordable. But the price of SSDs will undoubtedly drop in the coming years. The SSDs with large storage spaces will also become accessible. The hard disk will probably no longer be sold if this is the case.
But currently, a small SSD (512GB or smaller) for the operating system & programs and a large hard disk (1TB or more) for all your data is the ideal affordable combination.
FAQs
Q1: Do HDDs have any advantages to offer?
Some of the advantages include the following:
- Affordable
- Stores large amounts of data
- Durable
Q2: What are the disadvantages of HDDs?
- Take time to open large files.
- Use a lot of power
- Generate a lot of heat, making them less useful for laptop or notebook computers.
Q3: Do computers need hard disks?
Yes. Hard disks are needed to install programs, and operating systems, for saving documents & adding additional storage devices. Without it, computer users cannot store data once the computer is turned off, as it holds data permanently.
Q4: Are the hard disk drive and hard disk the same?
No. But they are packaged as a unit, and either term refers to both as a whole.
Q5: What is the difference between internal & external HDD?
Whether using desktop computers or laptops, your computer needs at least one data drive to function. Usually, the storage drive inside the computer case is internal and comes in various sizes. If your storage space is not enough, you can replace it. At the same time, an external drive attaches to your computer mainly through a USB port to increase storage space for back files, large files, music, or picture. In addition, it is portable, and you can move it to other computers to transfer files.
