【Creative Cultivation Program】Why do hard drives need to be partitioned?

Author: Zhou Lei

Reviewer: Chen Xudong

I believe that after buying a new computer, the first thing many people do is to open "My Computer" to partition the hard drive. Or they can divide the already partitioned C, D, E and other drives into different roles, with C for the system, D for software, E for data, etc. Why do we need to partition the hard drive? If we don't partition or the C drive is full, will the computer freeze?

For a long time after the birth of computers, there was actually no concept of partitions. In the beginning, computers did not even have "disks". All files and operating instructions were stored in semiconductors that acted as memory. After a power outage, all files would be reset. In order to solve the problem of data storage, in 1967, Alan Shugart, then an IBM engineer and later the founder of Seagate, invented the floppy disk.

At that time, to use a computer, people had to first insert the floppy disk with the operating system into the computer, copy the operating instructions into the semiconductor that served as the memory, and then insert the floppy disk that stored the data into the computer. Later, as the operating system became more and more complex, the memory capacity at the time was not enough to support the complex instructions. For the system to run normally, the floppy disk that loaded the system could not be disconnected, so computers with two floppy disk interfaces appeared, one for the operating system and one for the data. To distinguish them, the two disks were also named A and B. After the hard disk came onto the historical stage, it naturally became the C drive. After the floppy disk completed its historical mission and retired, the C drive, which was originally the third, also stood in the C position.

The difference between the previous A, B, and C disks and now is that they are all independent disks with different divisions of labor. Now, C, D, E, etc. disks are often divided into different areas of a disk. Since the capacity of the hard disk is enough to accommodate the operating system and various data, why do we need to partition?

Most early computers were equipped with mechanical hard disks, and their physical structure was generally composed of components such as magnetic heads and disks, motors, main control chips, and cables. The magnetic heads rotate on the disks through motors to read and write data. When the rotation speed is constant, the longer the circumference is on the outer edge, the faster the linear speed is, and the larger the area swept by the magnetic head per unit time is. The closer to the inner edge, the slower the linear speed is, and the smaller the area swept by the magnetic head is. For users, it means that the computer responds quickly or slowly. Therefore, in the period when mechanical hard disks were the main ones, it was more reasonable to partition the hard disk, put the operating system that needs to be started quickly on the C drive on the outer edge, and put the software and data on the D, E, F and other drives in turn according to the call frequency.

However, due to the physical characteristics of mechanical hard disks, there will be a "seek time" no matter which partition the data is written to. Simply put, this time refers to the time it takes for the head to move from the beginning to the track where the data is located. There are many factors that affect the "seek time", one of the important factors is disk fragmentation, that is, the various files that become fragmented when deleting written data. The more disk fragments there are, the more frequently the head needs to move to find the file location, which increases the "seek time". If the C drive is too full, the more disk fragments there are, and the system response time will also be longer.

In addition to improving computer operating efficiency, security is also an important reason for partitioning. Before Windows 8, due to the instability of the computer system, the system often crashed and needed to be reinstalled. If partitioning is used, reinstalling the system only requires formatting the system disk to avoid data loss in other partitions. However, after Windows 8, reinstalling the system will not format the system disk, but will transfer the data of the previous system to Windows.old.

In summary, in the era of mechanical hard disks, partitioning can improve computer performance and ensure data security to a certain extent due to the physical structure of hard disks. However, in the era of solid-state hard disks, since solid-state hard disks do not have the concept of seek, and read and write data do not require heads and disks, but read directly from Flash particles, partitioning is not very meaningful from the perspective of improving performance. However, from the perspective of data security and management, partitioning is still necessary.

References:

[1] Why do computer disk partitions now start from drive C? Where did drive A and drive B go?

https://zhuanlan.zhihu.com/p/386149246

[2] Technology Rings | Do you still remember the “floppy disk”?

https://www.sohu.com/a/231322713_641165

[3] Factors that affect the speed of mechanical disks: seek time, rotational delay, data transfer time

https://blog.csdn.net/xiaofei0859/article/details/49783205

[4] Popular Science | Do you still remember the disk partitions of the past?

https://www.sohu.com/a/233635248_641165

[5] My new computer is not partitioned properly. Is the manufacturer being lazy?

https://sspai.com/post/56920

This article is produced by the Science Popularization China-Creation Cultivation Program. Please indicate the source when reprinting