Clean room
A clean room is a workspace with filtered air, used when a hard disk drive has to be opened so dust does not settle on the platters.
A hard disk drive leaves the factory sealed. The gap between the read/write heads and the platter is far smaller than a speck of household dust. Opening the drive in an ordinary room lets that dust land on the surface. The next time the platters spin, a head can strike the dust and scrape the magnetic coating.
How does a clean room work?
Air is pushed through fine filters so loose particles are carried away instead of settling. People who work inside wear gowns, and tools are cleaned before they touch an open drive. The aim is to control dust. A clean room is not a hospital operating theatre, and shutting the office windows does not make one.
Why does opening a drive need a clean room?
The heads are meant to fly above the magnetic surface, not to rest on it. A fingerprint, a hair, or ordinary room dust is large enough to cause a head crash once the drive is spinning. A drive that has to be opened, for example to fit a replacement head, is opened in a clean room. A drive that is still sealed should stay sealed.
What should you do if you think a drive needs to be opened?
Leave the lid on. Do not undo the cover screws on a kitchen table or a workbench. Power the drive down and keep it still. Opening it in ordinary air is a common way for a drive that might still have been readable to pick up a scratch.
What might you notice if a drive has been opened?
- The cover screws have already been removed
- Someone has tried to swap parts with the lid off
- Dust or a fingerprint is visible on the platter
Related terms
Common misconceptions
Is a closed office clean enough to open a hard disk?
Office air still carries dust. The clearance inside a drive is much smaller than a particle you can see in a sunbeam. Filtered air is what keeps that dust off the platter.