Hard Disk Drive Design and Technology
Magnetic Hard Disk Drive (page 5)
Get a Hard Drive Data Recovery Quote
- Introduction
- Basic principles of magnetic recording
- Basic drive design
- Basic drive concepts
- Cache or Buffer
- Formatting
- File system
- Drive interfaces
- Drive installation
Basic drive concepts
Track
A concentric set of magnetic bits on the disk is called a track. Each
track is divided into 512 bytes (usually) sectors.
Sector
A part of each track defined with magnetic marking and an ID number.
Sectors have a sector header and an error correction code (ECC).
In modern drives, sectors are numbered sequentially.
Cylinder
A group of tracks with the same radius is called a cylinder (red tracks on
the picture belong to one cylinder).
Data addressing
There are to methods for Drive's data addressing: CHS (cylinder-head-sector) and LBA
(logical block address). CHS is used on most IDE drives, while LBA is used on SCSI and enhanced IDE
drives.
CHS locates addresses data by simply specifying the cylinder (radius), head (platters side), and sector (angular position). LBA assigns each sector of the drive a sequential number, which is simpler.
If you look into your BIOS, you will find listed the number of cylinders, heads, and sectors for each drive you have. Modern operating systems access data using LBA directly without the help of the BIOS. This reduces incompatibilities.
To improve performance and increase data rate, HDDs utilize a small amount of fast solid-state memory to store the most frequently used data. This memory is called 'cache' or 'buffer'. There are two types of cache memory organization: look-ahead and write / read.
>Back to Top