Why do HDDs have more memory than Discs?

jdub
Level: Silver

Best Answer

I think it has to do with the way data is written onto each medium. Discs like Blu-rays and DVDs use light to write, store, and read data. HDDs use magnetism.
They write information in two directions so it can be read as a 0 or 1. Also they have multiple platters (or discs) so it is more akin to having multiple Blu-rays stacked than just having a single one.
Another reason is that they are made out of metal, which has a higher density than plastic discs.
And finally they have to be very precise to read the data which is why you cannot drop them or shake them around.

There may be more reasons but those are the ones that I know.