Let’s say you are doing one thing easy like double-click on the icon for a spreadsheet file. this easy act, on several computers, will take twenty or thirty seconds to complete, and every one throughout that point the hard hard disk is churning away. The hard-hard disk access lightweight glints and therefore the drive would possibly create a whirring, whizzing or high-pitched whining noise. If the mechanism within the drive is loud, you certainly apprehend that one thing goes on!
In the article however exhausting Hard disks Work, you’ll be able to see that there’s Associate in Nursing arm that holds the read-write heads. This arm will move the heads to tracks close to the hub or close to the sting of the hard disk. a standard hard disk is five inches (12.5 cm) just about in diameter. This arm, therefore, will move regarding two inches (5 cm) across the face of the hard disk.
The speed at that this arm will move is astonishing. The arm is extremely lightweight, and its mechanism is powerful and precise. The arm will slide across the face of the hard disk many times per second if it must.
If you’re thinking that regarding however a speaker works, there’s not a lot of of a distinction. A speaker is moving a light-weight cone back and forth many times per second to get sound. because the hard-hard disk arm moves back and forth apace, it sets up vibrations that our ears hear as sounds.
Why, after you click on an easy computer program file, would the hard disk’s heads ought to move most (20 or thirty seconds value of movement sometimes)? There area unit 3 things that cause all the movement:
to begin a computer program application like stand out, the hard disk must load the appliance itself together with variety of DLLs (dynamic link libraries) that support the appliance. the full size of of these completely different files may be ten to twenty megabytes, and therefore the files area unit scattered everywhere the hard disk. Loading twenty megabytes of information takes lots of your time and needs the hard disk head to maneuver thousands of times to retrieve all the items.
the information file itself must load. The OS (OS) must move the pinnacle to the drive’s directory to seek out the folder, certify the file name exists, and so discover the situation of the file. Then the OS might have to browse dozens of tracks scattered everywhere the drive to access the file.
If the physical RAM is full, then throughout the loading method the OS can ought to unload components of physical RAM and save them to the paging file on the hard disk. therefore whereas the OS is making an attempt to load the computer program application and every one the DLLs and therefore the record, it’s at constant time making an attempt to write down scores of bytes of information to the paging file to form space for the new application. The drive head is moving everywhere the hard disk to accomplish these integrated tasks. See this Question of the Day for details.
Altogether, clicking on one icon might cause forty or fifty megabytes of information to maneuver between the drive and RAM, with the hard disk heads placement themselves thousands of times within the method. that’s why you hear the drive “churning” — it’s doing lots of work!