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I am currently learning about how HDD's function and in particular i am having trouble understanding what a Cylinder in a HDD is.

I have read online and my current understanding is that it is when a portition of the hard disk track is aligned with another track from another platter which contains similiar data such as a file.

but im not quite sure if that is even correct.

programmer
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    I'm voting to close this question as off-topic because it is a general hardware question unrelated to Unix & Linux as defined in the [help/on-topic] – Michael Homer May 09 '19 at 05:33
  • It is related to unix and linux beacuse in the linux parþed command it talks about cylinders and im not sure what they are.... – programmer May 09 '19 at 07:01

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If you look at the wikipedia explanation, a harddisk consists of several platters. Each platter has concentric tracks with data. The set of all tracks in the same position, for all platters, makes up a cylinder. It's called cylinder because it has the geometrical shape of a cylinder (well, more or less).

There is no relation to "containing similar data". None at all.

At least for early harddisks, the movement of the read-write-heads was coupled, so "cylinder number" was really a description for "how far do the read-write-heads have to move inside on all the platters".

Today, the head/sector/cylinder addressing is obsolete, and everyone uses logical block addresses (LBAs). The harddisk firmware is responsible for translating a LBA into head movements etc.

dirkt
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  • Ok so your saying that its when all the tracks are alligned in the same position. How does that even work? Arent tracks all the same size? – programmer May 08 '19 at 20:33
  • No. Sectors are the same size, but since tracks are concentric, inner tracks have fewer sectors each than outer tracks. – K7AAY May 08 '19 at 20:45
  • I'm not saying "all tracks are aligned in the same position". I am saying "the collection of all tracks in the same position (think: with a certain diameter) form a cylinder". Imagine a half-transparent (geometric) cylinder shape going "through" the stack of platters. Where the cylinder surface intersects with the platters, you have the tracks that make up the "hard-disk cylinder". – dirkt May 09 '19 at 12:24