What is a Head Crash?

The head crash is probably one of the most common hard disk drive faults we see in the data recovery lab. But what is a head crash, how are they caused, and what are the chances of a successful data recovery?

A head crash can occur when the read/write heads of a hard disk drive come into contact with the magnetic platter beneath. These heads are typically hovering a fraction of a millimetre above a thin pocket of air between them and the platter. A head crash can be caused by a shock to the hard disk drive, or even a small particle of dust or debris in between the heads and the platter.

Most modern hard disk drives spin at around 7,200 to 15,000 rpm, which can render the damage to the magnetic platters incredibly extensive. Even at the lower end of 7,200, the platters are spinning at around 74 miles per hour, and as you can imagine, the heads coming into contact with the platters at this speed isn’t a good sign. The best thing you can do if you suspect a head crash is to immediately power down your machine to prevent further damage. Time and time again, out data recovery technicians see hard drives that have suffered head crashes so severe, that none of the data is recoverable.

Data that is physically scraped off the platters is physically unrecoverable, unless you have a time machine. Because of the way hard drives store data randomly over a disk, this could be whole files or simply parts of many files. It is imperative to power down your computer or laptop if you hear a scratching noise. Head crashes are typically more common in laptops, which are moved around more than fixed desktop machines, although this has changed in recent years thanks to active heard drive protection, or “sudden motion sensing”.  Active heard drive protection attempts to reduce or completely avoid mechanical damage to hard disk drives by preparing the drive prior to impact. The technology is mainly utilised in laptops, which are moved around from location to location. A series of accelerometers alert the drive when vibration is detected, and the software then tells the hard drive to unload the read/write heads to prevent a possible head crash.

All of our data recovery work on hard drives that have suffered a head crash is undertaken in our Class 100 Clean Room lab, to ensure no further damage occurs. In the video below, the task was as simple as retrieving compatible donor parts from our library, and the data recovery was a success.