Computer hard drive
The computer’s hard drive (also known as HDD (Hard Disk Drive), it is also a hard drive, it is also a magnetic drive, it is also called “screw” and “hard”). Non-volatile storage of our collections of films and other files 🙂 “Non-volatile” in this case means that all stored information after turning off the power to the computer remains on the hard drive.
Computer hard drive
What are these functions (in addition to directly storing our data) performs a computer hard drive? We install all of our software on it. It also installs our most important program (a set of programs) – the operating system. Without an operating system, a computer is a heap of expensive iron, you understand 🙂 The computer’s hard drive also very often performs another important function, being (if necessary) an extension for the computer’s RAM. Especially – with a lack of the latter.
Let me explain with an example: Software running on a computer and performing some task requires 300 megabytes of memory to work, and currently only 250 are free (for example). The operating system makes a tricky move: it begins to “dump” long-requested data from the RAM into the computer’s hard drive, thereby freeing up space in RAM for the needs of the running program.
In fairness, it is worth noting that the overall speed of any task in this case begins to fall catastrophically. And this is logical. After all, the performance of the memory and the hard drive does not go to any comparison. A computer’s hard drive is much slower and the more data the operating system has to “dump” onto it from fast RAM, the more noticeable will be the overall performance drawdown.
If you take this process to the extreme, then a situation is possible in which almost any user action will be accompanied by convulsive attempts by the operating system to free up another portion of the RAM and copying another portion of the data to the hard drive. This can be visually determined by the constantly flashing red indicator of the hard drive on the front of the computer. The result is a very slow response of the system to any user actions (often resembles a hang) and a constantly flashing red light (LED) of the hard drive on the front panel of the case.
The situation described above is often characteristic of computer systems with insufficient RAM. More precisely, we formulate it this way: with insufficient memory for the tasks that are set before it 🙂
A few words about the misconception associated with a computer’s hard drive: many believe that there is a vacuum inside it, but it’s not. During the production cycle, the internal enclosed space of the disk (pressurized unit) is filled with air with a pressure of one atmosphere to create the effect of an “air cushion” between “pancakes” and reading and writing magnetic heads.
The requirements for air purity inside the pressure chamber (pressure zone) are quite strict. Dust particles larger than 0.3 microns (micrometer or micron) should not be present there. For comparison, the average thickness of a human hair is 40 microns. Now, I think, it is clear that the computer’s hard drive cannot be disassembled at home.
Inside the hard drive there is a spindle (axis) on which one or more magnetic pancakes are strung, which are located one above the other. Under this design is a motor that spins the spindle to the required speed.
Magnetic heads that perform read-write operations in the computer’s hard drive are combined into a block of magnetic heads (BMG), which simultaneously moves them all and is located above the desired cylinder of the hard drive. The BMG drive is called a positioner.
And now let’s “look under the lid” 🙂 So – the computer’s hard drive without a protective cover.
What we see here:
1 – a spindle that spins the hard drive plate.
2 – the magnetic plate of the hard drive itself is “damn” (where all our information is recorded)
3 – read-write head, which, moving a few microns from the surface of the disk and performs read-write operations.
If you completely disassemble the computer’s hard drive, then we will see this picture:
Hard Disk Drive Hard Disk Drive
There is another class of devices – external hard drives. It is, in fact, structurally the same hard drive, only more compact and hermetically packed in an anti-shock shell. Such drives are connected to the computer via a USB interface and act as “large flash drives” 🙂
External USB Hard Drive Connect External USB Hard Drive Connect