Low Level Format [Archive]

Joe Forster/STA

09-04-2021, 03:18

Just a question It is true Low Level Format no longer existe nowdays ??..

No, it doesn't, hard disks are so sophisticated today that you cannot erase all information from them and expect them to still work.

Imagine a vinyl record. There's a spiral groove in it. You can take a very thin nail and change the depth of the groove manually (changing the data = sound) but your normal vinyl player is unable to etch a new groove onto an unwritten record because the player can't etch (write) such a dense groove properly, only follow (read) an already existing dense groove.

On newer hard disks, tracks (not spiral grooves but concentric circles) are so dense that small changes in the temperature makes the read/write head expand/contract so much that they won't be able to follow tracks exactly. Also, some wobbling is expected when the read/write head must constantly move inwards/outwards slightly to follow the track because the center of the track circle may not be exactly the same as the platter's spin axis. The servo information that helps the read/write head to follow the track is written onto the disk surface in the factory - with a machine much finer, much more sophisticated and much more expensive -, it's not possible to rewrite it properly with a consumer hard disk. What you can do is change the information in the data tracks that are between the servo tracks. See https://en.wikipedia.org/wiki/Servowriter .