The Do Not Cover This Hole hole is a security feature on hard drives to protect data from being accidentally erased. ..
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The Question
SuperUser reader oKtosiTe noticed the warning label and needed to get to the bottom of things:
Thankfully no field studies or warranty voiding were required to solve the mystery.
What is the purpose of this hole and why would covering it cause damage or increase the likelihood of drive failure?
The Answer
Image courtesy of SuperUser contributor Oliver Salzburg.
SuperUser contributor music2myear offers some insight into the tiny hole and the importance of leaving it unobstructed:
Dennis expands on this explanation by directing us towards the section of Wikipedia dealing with hard drive integrity:
If the drive were completely sealed, operating at altitudes significantly different from those the drive was manufactured and sealed at, it would cause problems and increase the likelihood of catastrophic failures.
This system works in much the same way as the Eustachian tubes that allow our ears internal pressures to equalize, preventing the explosion of our ear drums.
The mere mention of headcrashes (and the horrible memory of the sounds our last lost-to-head-crash drive made) are more than enough warning for us.
Hard disk drives require a certain range of air pressures in order to operate properly. The connection to the external environment and pressure occurs through a small hole in the enclosure (about 0.5 mm in breadth), usually with a filter on the inside (the breather filter). If the air pressure is too low, then there is not enough lift for the flying head, so the head gets too close to the disk, and there is a risk of head crashes and data loss. Specially manufactured sealed and pressurized disks are needed for reliable high-altitude operation, above about 3,000 m (9,800 ft).[99] Modern disks include temperature sensors and adjust their operation to the operating environment. Breather holes can be seen on all disk drives—they usually have a sticker next to them, warning the user not to cover the holes.
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