What is the churning sound I hear from my hard drive whenever it is retrieving data?
Let’s say you do something simple like double-click on the icon for a spreadsheet file. This simple act, on many computers, can take 20 or 30 seconds to complete, and all during that time the hard disk is churning away. The hard-disk access light flickers and the drive might make a whirring, whizzing or high-pitched whining noise. If the mechanism in the drive is loud, you definitely know that something is going on! In the article How Hard Disks Work , you can see that there is an arm that holds the read-write heads. This arm can move the heads to tracks near the hub or near the edge of the disk. A normal hard disk is 5 inches (12.5 cm) or so in diameter. This arm, therefore, can move about 2 inches (5 cm) across the face of the disk. The speed at which this arm can move is astonishing. The arm is very light, and its actuator is powerful and precise. The arm can slide across the face of the disk hundreds of times per second if it needs to. If you think about how a speaker works, there
