Why is it written as “Do Not Cover this Hole” on Hard Drives?

If you have seen your hard disks present inside your desktop or your laptop then you must have come across a sticker or a note saying that “Do Not Cover this Hole” which would be pointing to a hole on the hard disk. This is there on every hard drive and is for some reason which most of us are not aware of.

No this hole is not acting as a heat sync and does not emit heat of the disk outside rather it is there for some reason that helps the disk for its normal operation. The disk hole is also not related to the warranty or something but have something important as mentioned below.

So what is the purpose of the hole on the disk and why should it be not covered?

The hole is actually used for maintaining the right air pressure in the disk. What happens is that, the drive, at the time of creation, is sealed at some optimum pressure and

it should have the same pressure at all places. The hole equalizes this air pressure inside and the outside of the disk.

The hole is not a clear pass through and in fact is fitted with a filter that allows the pressure to equalize. The drive couldn’t be completely sealed as this will prevent its use at some high/low pressure places as it would blow.

The right pressure in the disk allows the disk to function properly and the head to spin better. If the air pressure gets too low than it should be, the room for the flying head become low and it might get close to the disk which can cause the hard disk to crash. [via]

Source: http://techsalsa.com