Why does the disk arm and disk platter rotate? What occurs when each one iterates and do they tend to happen concurrently? This comes in the context of writing non volatile storage by moving a disk arm and waiting for the disk platter to rotate, but i'm not sure how these events lead to writing the storage system.

CodePudding user response：

The platter of a hard drive is covered in a very thin magnetic coating. The arm writes data to it by writing 1s and 0s as north and south poles of the magnet. The disk platter will always rotate because it is always being read from when the computer is turned on. The arm just moves to wherever it needs to write data. They do move concurrently but the movements are not connected because the platter spins all the time. The arm also reads data by viewing all of the north and south magnetic poles going by. Hope this helped!