What is the basic unit of disk read and write?

The basic unit of reading and writing a disk is "sector". The operating system uses blocks and clusters as units to read and operate data; sectors are the physical layer of the hard disk. Blocks and clusters are logical layers for the file system; the sector space is relatively small and numerous, making it difficult to address. The operating system combines multiple sectors to form a larger unit, and then perform overall operations on this unit.

The operating environment of this tutorial: Windows 10 system, Dell G3 computer.

What is the basic unit of disk read and write?

The basic unit of disk reading and writing is the sector, and the operating system uses blocks and clusters as units to read and operate data. Sectors are the physical layer for the hard disk, and blocks and clusters are the logical layer for the file system.

The sector space is relatively small and numerous, making it difficult to address. The operating system combines multiple sectors to form a larger unit, and then performs overall processing on this unit. operate. This unit is called a cluster in FAT, FAT32 and NTFS file systems under Windows; it is called a block in file systems such as Ext4 under Linux.

Extended information:

Today’s disks use ZBR (Zone Bit Recording) technology. The surface of the disk is divided into several areas from the inside out. The number of track sectors in different areas is different. , the number of sectors in each track in the same area is the same, the outer area of ​​the disk has more long sectors, and the inner area has fewer short sectors, roughly achieving equal density, thus obtaining more storage space.

Most products are divided into 16 areas, and the number of sectors per track in the outermost circle is exactly twice that of the innermost circle (373~746). When the disk spindle motor rotates at a certain speed (N revolutions per second), the further outward, the greater the linear speed, the more sectors scanned per unit time, and the higher the read and write speed.

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