Concepts related to mechanical disks: track, cylinder, sector, track seeking time, rotation delay, and data transmission time

(I) Track

The circle is centered on the disc and different radius are used to divide different narrow circular areas.

(Ii) slice

Each track on the disk is divided into several arc segments, which are the disk sectors. The sector is the smallest physical storage unit of the disk.

(Iii) cylindrical

A cylindrical Ring Wall Composed of tracks with the same radius in the upper and lower disks is called a cylindrical

The previous image is more intuitive

(Iv) Seek time

HeadMove from start to Data LocationTrackRequired Time
The shorter the tracing time, the faster I/O operations. Currently, the average tracing time of a disk is generally 3-15 ms,The current server can be 3 ms

(V) Rotation Delay

Disk rotation stores the requested dataSliceMove to read/writeHeadTime required below
Rotation delay depends onThe disk speed and current server can reach 15000 rpm

(Vi) data transmission time

The time required to transmit the requested data

Summary:

From the above indicators, the most important thing is that we are most concerned about only two:

● Seek time

● Rotation Delay