Take notes on the drive part of the block device.

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For Block devices, first define several basic concepts:

Sector (sectors): Usually 512 bytes. It is the basic unit for hardware devices to transmit data.

Block (blocks): usually 1, 2, 4, 8,... slice, and smaller than one page. It is the basic unit for the kernel (VFS and file system) to transmit data.

Segment: it is a number of adjacent blocks. It is a part of a memory page or memory page. It is generally driven by Block devices.ProgramTo process.

Each buffer corresponds to a block, which is equivalent to the representation of the disk block in the memory.

Reference a graph in ulk3 to illustrate their relationship:

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For the layered architecture of the entire block device driver, a figure in ulk3 can clearly describe these:

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