What is HDD?

We, users of a personal computer, often encounter the abbreviation HDD. And it's justified to want to know what HDD is, where it is and what it's for.

HDD stands for "hard disk drive". Simply put, it's a hard drive. Gradually disappearing into the past, they are being replaced by SSD, but their niche in the HDD market will take a long time to come.

Why is the hard drive

HDD in the computer as soon as not called. Hard disk, hard drive, hard drive, screw - only a small list of its names. Why all the same "hard disk drive"?

Unlike "floppy" disks (floppy disks), data onHDDs are written to hard plates, and they, in turn, are covered with a layer of ferromagnetic material. They are called "magnetic disks" only. The hard disk uses one or more plates on one axis. The reading devices (heads) do not touch the surface of the plates. This is explained simply: with rapid rotation of the plates a layer of the incoming air flow is formed. The distance between the reading device and the working surface is very small - only a few nanometers, and the air layer, which excludes mechanical contact, ensures a long service life. If the plates do not rotate at the proper speed, then the heads are in the so-called "parking" zone - outside the boundaries of the plates.

A distinctive feature of HDD in the computer is that the information carrier is combined with the drive, as well as with a block of necessary electronics in one housing.

Main characteristics of HDD

Like any technical device, the hard drive has a number of characteristics, from which it can be concluded that it is relevant.

  • Capacity is one of the most significant values. Characterizes the amount of data that can be stored by the drive.
  • Dimensions (form factor). The most common variations are 3.5 and2.5 inches. Specifies the width of the device.
  • Rotational speed of the axis, spindle. The number of revolutions per minute. The parameter significantly affects the speed of access to data and directly to the speed of their transmission. The most common options are 4200, 5400, 7200, 10,000 rpm.
  • The number of I / O operations per second. With modern disks, this number is approaching 50 (with random access to data), with sequential access, respectively, higher - about 100.
  • Power consumption is an important parameter for portable devices (we are talking about laptops / netbooks).
  • The size of the buffer. The buffer is an intermediate memory. Its purpose is to smooth the differences in read / write speed. In modern HDD usually located in the range of 8 to 64 megabytes.

I hope we were able to figure out what HDD is in the computer, and even expand our horizons in the world of computer hardware.

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