The flying height or floating height or head gap is the distance between the disk read/write head on a

hard disk drive A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magne ...

and the platter. The first commercial hard-disk drive, the

IBM 305 RAMAC The IBM 305 RAMAC was the first commercial computer that used a moving-head hard disk drive (magnetic disk storage) for secondary storage. The system was publicly announced on September 14, 1956,

, used forced air to maintain a 0.002 inch (51 μm) between the head and disk. The IBM 1301, introduced in 1961, was the first disk drive in which the head was attached to a "hydrodynamic air bearing slider," which generates its own cushion of pressurized air, allowing the slider and head to fly much closer, 0.00025 inches (6.35 μm) above the disk surface. In 2011, the flying height in modern drives was a few nanometers (about 5 nm). Thus, the head can collide with even an obstruction as thin as a fingerprint or a particle of smoke. Despite the dangers of

hard drive failure A hard disk drive failure occurs when a hard disk drive malfunctions and the stored information cannot be accessed with a properly configured computer. A hard disk failure may occur in the course of normal operation, or due to an external factor ...

from such foreign objects, hard drives generally allow for ventilation (albeit through a filter) so that the air pressure within the drive can equalize with the air pressure outside. Because disk drives depend on the head floating on a cushion of air, they are not designed to operate in a vacuum. Regulation of flying height will become even more important in future high-capacity drives. However,

hermetically sealed A hermetic seal is any type of sealing that makes a given object airtight (preventing the passage of air, oxygen, or other gases). The term originally applied to airtight glass containers, but as technology advanced it applied to a larger categor ...

enclosures are beginning to be adopted for hard drives filled with

helium Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. ...

gas, with the first products launched in December 2015, starting with capacities of 10 TB.

References

{{reflist Hard disk drives

See also

References