Linux Disk Management knowledge

First, the basic knowledge of hard disk

1. Hardware structure of hard disk

External structure:

Internal structure:

Component Introduction:

Head: Is the most expensive part of the hard drive, the use of non-contact structure, power after the suspension in the high-speed rotation of the disk surface, there is a read-write and read-write separation of two forms.

Track: When the disk rotates, if the head remains in the same position, each head on the disk formed a circular trajectory, these circular trajectory is called the track.

Cylinder: A plurality of disks that overlap in a disk and are formed at the same radius are superimposed to form a cylindrical surface.

Sector: A plurality of arc segments on a track, and a sector-like region formed by a center is called a sector.

2. The working principle of the hard disk

The disk uses the polarity of specific magnetic particles to record data, the magnetic head converts the different polarity of the particles into different electrical pulse signals, and then converts the data into 0 and 1, which can be recognized by the computer, to realize the data reading and writing and erasing.

3. Main parameters of hard disk

Capacity: As a computer system data memory, capacity is the most important parameter unit of the hard disk: MB/GB

Rotational speed: Refers to the hard disk disc rotation per minute of the number of laps, units: rpm (Revolutions each minute)

Mean seek time: the time that the head moves to the track where the data resides, which is an important indicator of the mechanical performance of the hard disk.

Data transfer rate: the speed at which the hard disk reads and writes data, in megabytes per second (MB/s)

Disk buffer (Cache): Primarily used to balance internal and external data transfer rates

4. The hard disk related interface introduction

IDE: Electronic Integrated Drive, an early hard drive interface that is rarely used at low prices and with good compatibility.

SCSI: Small computer system interface, is a bus-type system interface, the adaptation surface is quite wide.

SATA: Serial ATA interface that transmits data in a serial manner, can be connected one-on-one, enjoys exclusive bandwidth and supports new technologies such as hot Plug and unplug

SAS: The same as SATA, the use of serial technology to achieve higher transmission speed, and improve the internal space by shortening the connector line.

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