The difference between solid-state drives and mechanical hard drives

Storage principle
Solid state drive (SSD): uses flash memory chips to store data. Based on flash memory electronic storage technology, data reading and writing are achieved by controlling the transistors inside the flash memory chip through electrical signals, and the data is stored in the flash memory unit of the chip.
Mechanical hard disk (HDD): It performs data read and write operations on high-speed rotating disks through magnetic heads. The surface of the disc is coated with magnetic material, and the magnetic head moves to the designated position of the disc under the drive of the motor, using magnetic principles to store and read data.

Performance Performance
Read and write speed:
Solid state drive: extremely fast read and write speed, especially 4K random read and write speed. The sequential read speed can easily reach several kilobytes per second (MB/s), and the random read speed can also reach a high level. This enables system startup, software loading, and file transfer operations to be completed in a short amount of time.
Mechanical hard drive: The read and write speed is relatively slow, with sequential read speeds generally around 100 megabytes per second, and random read and write speeds significantly lower than solid-state drives. Due to its mechanical structure limiting the speed of data access, the magnetic head needs to be moved to the corresponding position on the disc in order to read the data.
Data access latency:
Solid state drive: Due to the absence of mechanical components, data access latency is extremely low, typically within a few tens of microseconds.
Mechanical hard disk: Due to limitations in disk rotation speed and head seek time, data access latency is relatively high, typically ranging from a few milliseconds to over ten milliseconds.

Stability and durability
Solid state drive: Without mechanical components, it has strong shock resistance, and the risk of data loss is relatively small when subjected to vibration or collision. However, flash memory chips have a write life limit (P/E times), and the P/E times for TLC flash memory are generally around 1000 to 3000 times. However, through technical means, its service life can be extended to a certain extent.
Mechanical hard drive: It has high-speed rotating disks and moving magnetic heads inside. When subjected to severe vibrations, the magnetic heads may scratch the disks, resulting in data loss. However, if used normally and in a good environment, mechanical hard drives can also be used for a longer period of time.

Capacity and price
Solid state drives: have relatively small capacities, commonly including 128GB, 256GB, 512GB, 1TB, etc. However, with the development of technology, there are also more and more high-capacity solid-state drives. In terms of price, the price per GB is relatively high but showing a downward trend.
Mechanical hard drive: Large capacity, commonly available in 1TB, 2TB, 4TB or even higher capacities. The price per GB is relatively low, suitable for users who have high storage capacity requirements but not particularly high read and write speed requirements.

Application scenarios
Solid state drive: Due to its fast read and write speed, it is suitable as a system disk and for installing commonly used software, which can greatly improve the system's startup speed and software running efficiency. It is also suitable for work scenarios that require extremely high read and write speeds, such as design, video editing, and other fields.
Mechanical hard drive: suitable for data storage, such as storing large amounts of files, photos, videos, and other data warehouses. In scenarios where read and write speed requirements are not high, such as monitoring storage, mechanical hard drives have significant advantages in large capacity and low cost.